United Nations (Agencies): UN chief Ban Ki-moon has slammed the use of violence to suppress anti-government protests in the Middle East, and asked the Arab leaders to instead "learn lessons and deliver bold reforms".

"I will say it once again: the situation calls for bold reforms, not repression," Ban told reporters.

Commenting on the violent police raid on pro-democracy protesters in Bahrain, the UN Secretary General said: "The reports from Bahrain overnight are deeply troubling. Here as elsewhere, violence should not be used against peaceful demonstrators and against journalists".

"It must stop," he added, calling on those responsible to be brought to justice.

He said the protests had been sparked by people's frustration at the lack of jobs and the lack of freedom of expression, assembly and communication and of not being able to participate in their country's political process.

"We have seen the wide (spread) demonstrations, outbursts of demonstrations and voices are now on the streets.

That means they have been frustrated enough by the lack of freedom, lack of opportunities.

"That is the lesson, which the leaders should learn and try to change, as soon as possible, reflecting such strong voices from their own people," he said.

Pro-democracy protests have raged in the Arab world ever since successful uprisings in Tunisia and Egypt threw out autocratic regimes. Protests have been witnessed in Libya, Bahrain, Algeria, Yemen and Jordan.

The US administration, meanwhile, asked Bahrain not to use force against peaceful protesters, as the army in the tiny Gulf kingdom vowed "strict measures" to restore order after a violent raid on anti-regime demonstrator’s left four people dead and scores wounded.

"We oppose the use of violence in Bahrain," White House spokesman Jay Carney told reporters, adding that the US calls on the government of Bahrain to "show restraint in responding to peaceful protests."

Secretary of State Hillary Clinton called her Bahrain counterpart Sheikh Khaled bin Ahmad al-Khalifa to express her deep concern about recent events and urged restraint.

Senator John Kerry, Chairman of the powerful Senate Foreign Relations Committee, in a letter to King Hamad of Bahrain expressed his strong opposition to use of force against peaceful protesters in his country.

Commenting on Egypt where anti-regime protests toppled longtime president Hosni Mubarak, Ban said there must be a transition from the present military leadership to the democratic civilian rule following free and fair elections.

"Those commitments must be fulfilled. There must be no turning back," Ban said.

In the days ahead, he said he would be "reaching out" to leaders to reiterate the message that they should "listen attentively to the people and to respond to their legitimate aspirations."