(CNN) -- Bahrain´s King Hamad bin Isa al-Khalifa has imposed a three- month state of emergency in the island nation, effective Tuesday, according to the state news agency.

The moves comes amid uncertainty in Bahrain, after foreign troops arrived to help the government quell weeks-long protests in the Persian Gulf kingdom.

Saudi Arabia and the United Arab Emirates sent troops Monday to "protect the safety of citizens," the Bahraini government said.

But some in the capital city said Tuesday they did not need the added protection.

"We don´t understand why these troops are coming in," said a 28-year- old blogger in Manama. "We have an army and police. We do not need troops from other places. Opposition leaders have called this an invasion. An act of war."

Like others in this report, the blogger said he did not want to be named because of fears of retribution.

Another man from the town of Hidd, who wanted to be identified only by his first name, said he feared the troops would just inflame the already tense standoff.

"I really hope things work, but I don´t think foreign troops will solve anything," said Abdulrahim. "It will probably lead to more violence."

But a 25-year-old banker from Manama said she welcomed the presence.

"It gives us peace," the woman said. "Maybe these protests will finally end. These protesters say they are peaceful, but I have seen them carrying sticks and knives. They are blocking the streets so we cannot get to work. They are criminals and this has gone on for too long."

The protests, which started on February 14, are part of a series of demonstrations that have swept across the Arab world this year, toppling the leaders of Tunisia and Egypt. But it was not clear whether any other country had taken the step of calling in foreign troops for help.

The movement of forces came on the same day that protesters seized control of a key part of the capital city, Manama, a Human Rights Watch official said.

Medical officials said at least 36 people were injured in clashes Monday, many of them wounded by projectiles from pellet guns.

The Bahrain Financial Harbour was still shut down Tuesday morning, said Faraz Sanei, a researcher with the group. But the extra troops were not visible in the city.

"There are areas of the city that are being controlled by vigilante groups armed with sticks and batons. The patrols seem to be sectarian," he said.

"Any time civilians take up arms and take matters into their own hands or threaten violence it is of great concern," regardless of their political affiliation, Sanei said.

The nation´s Independent Bloc of lawmakers called on Bahrain security forces to intervene to protect national security and stability, the Bahrain News Agency reported Sunday. The bloc is composed of the 22 pro-government members of the lower house of the legislature.

"Extremist movements are resorting to escalation and sectarian mobilization, which led to an unprecedented disruption of security and hostile sectarian polarization at health and educational institutions," the group said in a statement.

On Sunday, clashes between protesters and security forces resulted in the hospitalization of more than 1,000 people, human rights activists said.

The unrest prompted the U.S. State Department to warn Americans to consider leaving the island nation. The United Kingdom, too, has urged its residents not to travel there.

Last month, U.S. President Barack Obama welcomed plans by King Hamad to make changes to his cabinet and proceed with reforms.

But a few days ago, U.S. Defense Secretary Robert Gates cautioned that "baby steps" would not be sufficient to meet protesters´ demands.

Bahrain is the key banking and financial center in the Gulf. It also plays a crucial role in U.S. defense interests in the region. The U.S. Fifth Fleet is headquartered in Bahrain, and Bahrain is the only Arab state to have led one of the coalition task forces that patrol the Persian Gulf. U.S. military access to Bahrain also supports operations in Iraq.

An underlying concern in this issue is that Iran, an overwhelmingly Shiite state, could seize the opportunity to meddle in Bahrain´s internal affairs. Bahrain has a Shiite Muslim majority population, but its rulers are Sunni Muslims.

On Tuesday, an Iranian Foreign Ministry official criticized the arrival of Saudi troops as an "invasion," Iran´s Press TV reported Monday.

Saudi Arabia´s eastern province is home not only to many of the country´s rich oil fields but to its largest concentration of minority Shiites as well.

In recent weeks, Shiite demonstrators there have protested the Saudi government, whose leaders are overwhelmingly Sunni.

The Saudi government would presumably be concerned that any uprising by Shiite Muslims in Bahrain could inspire the Shiite population in nearby Saudi Arabia to follow suit.

During protests in Bahrain, moderates have been demanding a constitutional monarchy, and hardliners have called for the abolition of the royal family altogether.

But pro-government members of parliament have asked King Hamad to enforce a curfew and deploy security forces across the country, saying the protesters´ motives are far more sinister.

"What we are witnessing in Manama is no peaceful protest," Bahrain´s Foreign Minister Khalid al-Khalifa said on Twitter. "It´s (a) wanton, gangster-style takeover of people´s lives." CNN´s Jenifer Fenton contributed to this report (© 2011 Cable News Network 03/15/11)