Pressure is mounting for Syrian president Bashar al-Assad to quit his nation as Western and Arab nations indicate they are willing to broker a deal for his exit.

"We do believe that it is not too late for the Assad regime to commence with planning for a transition to find a way that ends the violence," Secretary of State Hillary Clinton said Tuesday, according to wire reports.

Clinton´s comments come after her close friend, Senate Intelligence Committee Chairwoman Dianne Feinstein, a California Democrat, also voiced support for getting Assad out of Syria.

The Arab League on Monday directly offered Assad and his family a safe exit from Syria if he agreed to leave the country.

The offer comes despite UN High Commissioner for Human Rights, Navi Pillay, having said earlier this year that there was ample evidence to prosecute Assad for war crimes.

Reports of systemic kidnapping, rape, torture, and summary executions carried out by regime forces and allied militias to quell Syria´s revolt have become commonplace in recent months.

Meanwhile, signs that Assad´s regime is teetering on the brink after 16-months of bloodletting in Syria´s popular Arab Spring uprising turned civil war continue to emerge.

Al Jazeera reported on Tuesday that the Syrian ambassador to Cyprus had defected and left for Qatar.

Lamia al-Hariri is the second Syrian diplomat to join the opposition, following Nawaf Fares, the ambassador to Iraq, who defected earlier in July. Fares was also reported to be in Qatar.

The new defection came as reports of intensified fighting continue to emerge from the capital of Damascus and key economic center of Aleppo. Opposition groups claimed warplanes, seen circling high above, had launched airstrikes in Aleppo on Teusday, as deadly clashes continue to leave scores dead each day.

"The rebels have moved to try and liberate downtown after taking over the neighbourhoods of al Sakhour, Masaken Hanano, Tariq al Bab, al Sheikh Najajr and al Ard al Hamra in the east and Saladin in the west," an opposition activist in Majed al Nour said.

Opposition activist Mohammed Saeed has estimated the rebels are holding large chunks of the city and the government has responded with attack helicopters.

The use of attack helicopters to target dissidents and rebel fighters by the embattled regime of President Bashar al-Assad has proven key to his holding the capital of Damascus.

"Helicopter and tank shells are falling on areas in the outskirts of Aleppo, which came under the control of the rebels," activist Abu Haytham al-Halabi told dpa by phone.

"On the ground, troops were defeated by the rebels but they are now using their helicopters to bombard those areas," he said.

Nevertheless, rebel fighters from the Free Syrian Army have turned Syria´s once impregnable leading cities into fiercely contested battlegrounds in recent weeks.

"It´s like a real war zone over here, there are street battles over large parts of the city," Saeed told reporters.

"Aleppo has joined Homs and Hama and other revolutionary cities."

The United States has flowed some funds to the rebels, and assisted with other items like intelligence data.

But opposition sources say Washington has yet to turn over tens of millions of dollars in frozen Assad regime dollars promised to rebel factions months ago.

Sources say promised communications gear also has yet to arrive in the hands of opposition fighters.

Officials in Washington have been reticent to openly arm and equip Syria´s disparate rebel factions out of concern the munitions may fall into the hands of anti-American terror groups.

Saudi Arabia has been supplying opposition forces with weapons, which sources and experts say have helped rebel fighters score a spate of recent victories over Assad´s forces. Earlier this week,Assad´s regime has threatened to use chemical weapons should outside forces seek to aid Syria´s rebels in toppling his regime.

FSA commanders in Syria say Assad has moved his chemical weapons stores to airfields near the borders.

"Most of us in the Free Syrian Army command know very well where these weapons are located," Colonel Kassim Saadeddine told Al Jazeera.

"And now we have solid information that Assad has transferred some of these weapons with the equipment for mixing chemical components to airports near the border," he added.

The London-based Syrian Observatory for Human Rights say at least 19,000 people - most of them civilians - have been killed in Syria since violence erupted March 2012. (IsraelNationalNews © 2011 07/24/12)