A deadly crackdown on protesters in Libya has prompted the United Nations Security Council to impose sanctions on the regime of Moammar Gadhafi, hours after U.S. President Barack Obama urged the North African leader to step down.

The 15-member Security Council voted unanimously to adopt a resolution that includes a travel ban and an asset freeze for Gadhafi, his family and senior members of his government.

It also calls for the ongoing crackdown on protesters in Libya to be referred to the International Criminal Court (ICC) in The Hague, opening the door for anyone who has killed civilians to be investigated and possibly placed on trial.

The resolution deplores "the gross and systematic violation of human rights, including the repression of peaceful demonstrators" in the country and rejects "unequivocally the incitement to hostility and violence against the civilian population made from the highest level of the Libyan government."

The fighting in Libya has become the bloodiest against anti-government protesters since a wave of popular unrest erupted across North Africa and the Middle East several weeks ago.

By some counts, more than 1,000 people may have died in fighting between protesters and pro-Gadhafi forces, many of whom are reportedly hired mercenaries from other African countries.

Earlier on Saturday, U.S. President Barack Obama called on Moammar Gadhafi to do "what is right" for Libya by "leaving now." Obama made the remarks in a private phone call with German Chancellor Angela Merkel.

"When a leader's only means of staying in power is to use mass violence against his own people, he has lost the legitimacy to rule and needs to do what is right for his country by leaving now," Obama said, according to a statement from the White House.

The violence in Libya has prompted outrage from many world leaders and has led to mounting diplomatic pressure on its 68-year-old autocratic leader.

On Friday, the White House froze all assets in the U.S. belonging to Gadhafi, his children and his government, and barred American defence firms from doing business with Libya.

UN deliberations

Many of the Security Council's members reportedly agreed that new sanctions were warranted, but there may have been initial disagreement over the proposal to refer Gadhafi to an international war crimes tribunal.

UN Secretary-General Ban Ki-moon had urged the council to take immediate steps to protect civilians in Libya.

"In these circumstances, the loss of time means more loss of lives," Ban said Friday.

He continued campaigning Saturday for international support to boost pressure on Gadhafi, calling King Abdullah of Saudi Arabia and Italy's Premier Silvio Berlusconi.

Libya's own mission to the UN has renounced Gadhafi, and wrote in a letter to the council that it supports "the measures proposed in the draft resolution to hold to account those responsible for the armed attacks against the Libyan Civilians, including through the International Criminal Court."

Meanwhile Paul Heinbecker, a former Canadian ambassador to the UN, warned that the resolution would not likely have an immediate effect on violence in Libya, regardless of whether it mentioned the ICC.

"Nothing like that is going to save anybody's life in Tripoli today," he told CTV News Channel on Saturday afternoon.

Some of the language Gadhafi has used in recent speeches "is the kind of language we heard also in Rwanda and we know how that finished -- very badly," Heinbecker warned.

Discussion about possible military action remained fuzzy at the UN. NATO has also rejected the idea of intervening.

With files from The Associated Press