(Reuters) - The U.N. Security Council, including Russia and China, threw its weight on Wednesday behind efforts by Kofi Annan to end the bloody conflict in Syria, providing a rare moment of global unity in the face of the year-long crisis.

In a statement approved by all its 15 members, the council threatened Syria with unspecified "further steps" if it failed to comply with Annan´s peace plan, which calls for a ceasefire and demands swift access for aid agencies.

Although the original statement was diluted at Russia´s demand, editing out any specific ultimatums, the fact that all world powers signed up to the proposal dealt a serious diplomatic blow to President Bashar al-Assad as he battles a popular uprising.

"To President Assad and his regime we say, along with the rest of the international community: take this path, commit to it, or face increasing pressure and isolation," U.S. Secretary of State Hillary Clinton said in Washington.

The conflict spilled over Syria´s borders late on Wednesday when several shells hit the Lebanese border village of al-Qaa and nearby fields, injuring one person, residents said.

Al-Qaa, 10 km (six miles) from the Syrian border, has been the first stop for many of the 7,000 Syrian refugees who have fled fighting into Lebanon.

Refugees complain that they are pursued by Syrian forces, who have often fired across the border, but al-Qaa residents said this was the first time artillery has been used.

Adding to the pressure on Damascus, European Union governments are set to impose sanctions on Assad´s wife Asma on Friday, EU diplomats said, meaning that she will no longer be able to travel to the 27- nation bloc or buy products from EU-based shops in her own name.

The sanctions, which still need formal approval from ministers, come after the British-born former investment banker became the focus of media attention when a trove of emails obtained by Britain´s Guardian newspaper appeared to show her spending tens of thousands of dollars on internet shopping sprees while Syria descended into bloodletting.

At least 8,000 people have died in the revolt, according to U.N. figures. Violence has intensified in recent weeks as pro-government forces bombard rebel towns and villages, looking to sweep their lightly armed opponents out of their strongholds.

Assad´s forces have chalked up a string of gains as they turned their firepower on areas held by rebels. But the fighting shows no sign of abating and analysts expect the insurgents to change their tactics and adopt guerrilla warfare.

32 KILLED ACROSS SYRIA

The British-based Syrian Observatory for Human Rights said 32 civilians were killed in Syria on Wednesday, the majority in government shelling on towns in Syria´s central Homs province.

The army fired mortars into the Khalidiya district of Homs city, while artillery targeted the rebel town of Rastan, north of Homs city. Video also showed shelling of the ancient Apamea castle at Qalat Mudiq, near Hama.

Opposition activists said the army used tanks, artillery and anti- aircraft guns on the Damascus suburbs of Harasta and Irbin early Wednesday, which were retaken from rebels two months ago but have seen renewed insurgency in recent days.

The official Syrian news agency SANA reported the funerals of seven security force members killed in the fighting.

Reports from Syria cannot be independently verified because officials have barred access to rights groups and journalists.

Russia and China, competing with Western powers for influence in the Middle East, previously vetoed two U.N. draft resolutions that would have condemned Damascus and have resisted calls from Western and Arab states for Assad to stand down.

But faced by growing global outrage at the bloodshed, the two countries agreed to a so-called "presidential statement". They are generally non-binding documents but do require unanimous support in the Security Council.

Russia, one of Assad´s few remaining allies, praised the document as pragmatic. "The most important thing is that there are no ultimatums ... and no suggestions as to who carries more blame," Foreign Minister Sergei Lavrov said in Berlin.

DEMANDS

The accord came a few days after Annan, a former U.N. secretary general, told the Security Council that the response by Damascus to his plans for peace were disappointing and he had urged the international community to lay aside its divisions.

His proposal, spelled out in the U.N. statement, tells the Syrian government to cease troop movements in population centers and end the use of heavy weapons in such areas.

It also calls for the government and opposition to hold talks to secure a peaceful settlement. Assad has not rejected the proposals but has challenged their feasibility and asked who can speak for the splintered opposition.

The Syrian opposition plans to meet in Turkey on March 26 to try to overcome their internal feuds and plot a more coherent strategy, sources said on Wednesday.

However, they have yet to agree on who should attend the gathering, underlining doubts about their ability to act in concert, which has frustrated Arab and Western states seeking a reliable partner to unite the anti-Assad movement.

The Security Council last passed a presidential statement on Syria in August 2011, but council members did reach a rare agreement on March 1 to rebuke Damascus for not letting U.N. humanitarian aid chief Valerie Amos into the country.

Shortly afterwards, Amos was allowed to visit Damascus.

Annan welcomed the U.N. support for his mediation efforts and called on Damascus to "respond positively".

The latest Council accord came after Moscow adopted a new, sharper tone with Syria, which hosts Russia´s only naval base outside the former Soviet Union.

"We believe the Syrian leadership reacted wrongly to the first appearance of peaceful protests and ... is making very many mistakes," Lavrov told Russian radio on Tuesday.

France welcomed the Security Council´s move and said Assad must now halt all violence and repression, allow humanitarian aid to reach everyone in need and engage in "inclusive dialogue" with the opposition to find a lasting political solution.

"With this declaration the United Nations Security Council is beginning to take responsibility after months of blockage," French Foreign Ministry spokesman Bernard Valero said in Paris.

(Additional reporting by Louis Charbonneau in New York, Dominic Evans and Jamal Saidi in Beirut, Steve Gutterman in Moscow, and Olivia Rondonuwu in Jakarta, Leigh Thomas in Paris, Justyna Pawlak in Brussels; Writing by Oliver Holmes and Crispian Balmer; Editing by Mark Heinrich) (© Thomson Reuters 2012. 03/21/12)