WASHINGTON – US President Barack Obama told the world Wednesday to unite to hold Libya accountable for a vicious protest crackdown, stiffening a US response to the crisis that critics had cast as too mild.

In his first televised response to Libyan leader Moamer Kadhafi's decision to unleash vengeance on demonstrators, Obama reached out to US allies and promised to deploy a "full range of options" to halt "outrageous" bloodshed.

Obama spoke as officials said that Washington was considering fresh sanctions and other steps against Libya, and as political pressure mounted on his administration for a more activist response.

The administration's careful previous line on violence that a former Libyan minister said had killed 1,000 people, appeared to be dictated by fears that American diplomats and citizens in Libya could face reprisals.

But by late Wednesday, a US-chartered ferry with a capacity of 575 passengers was riding out bad weather in Tripoli harbor before casting off on an evacuation mission to Malta.

"The suffering and bloodshed is outrageous, and it is unacceptable," Obama said at the White House.

"So are threats and orders to shoot peaceful protesters and further punish the people of Libya. These actions violate international norms, and every standard of common decency. This violence must stop."

Obama defended his administration against claims that its response to the violence, the latest wave of unrest crashing across the Middle East, had been too tempered.

"Over the last few days my national security team has been working around the clock to monitor the situation there and to coordinate with our international partners about a way forward," he said.

But the president did not mention Libya's ruthless and unpredictable leader Kadhafi, who has ruled for decades and frequently defied the United States, by name.

Seeking to corral international action on Libya, Obama said that in such a volatile situation, it was "imperative" for nations to speak with one voice.

He said he would dispatch Secretary of State Hillary Clinton to a ministerial-level meeting in Geneva on Monday of the UN Human Rights Council.

"Like all governments, the Libyan government has a responsibility to refrain from violence, to allow humanitarian assistance to reach those in need and to respect the rights of its people," Obama said.

"It must be held accountable for its failure to meet those responsibilities and face the cost of continued violations of human rights."

Though officials said that sanctions were among options being discussed, it was unclear whether calls for NATO to establish a "no fly zone" over Libya to protect civilians were on the table.

Obama's call to US allies appeared to be a signal that Washington, which has sought not to inject itself into the Middle East revolts, preferred the safety in numbers of multilateral action.

Europe had already moved Wednesday to isolate Kadhafi, readying sanctions that one diplomat said could include an assets freeze, a travel ban, an arms embargo and the legal pursuit of those involved in violent repression.

Washington lifted sanctions on Libya in 2004 under a deal which helped the former pariah state back into the global community after it gave up its nuclear and chemical weapons programs.

Influential US lawmakers, including Democratic Senate Foreign Relations Committee chairman John Kerry and his Republican House of Representatives counterpart Ileana Ros-Lehtinen have called for US sanctions to be reimposed.

US officials apparently feared that robust US rhetoric on the crisis could have made the plight of Americans even more perilous than that of other foreigners, given the tortured recent history between Washington and Tripoli.

In 1986, then president Ronald Reagan sent US warplanes to bomb Libya, in retaliation for the bombing of a discotheque in West Berlin. Kadhafi's adoptive daughter was killed in the US raids on Libya.

On Wednesday, Libya's former justice minister Mustapha Abdeljalil told the Swedish daily Expressen, that Kadhafi had then personally ordered the bombing of a US Pan Am jet over Lockerbie, Scotland in 1988, that killed 270 people.