ISTANBUL — More than 30 nations, including the United States, on Friday declared that Libyan leader Moammar Gadhafi's regime is no longer legitimate and formally recognized Libya's main opposition group as the legitimate government until a new interim authority is created.

The decision will keep up the military pressure on Gadhafi and potentially free up cash that the rebels fighting Libyan forces urgently need. The front lines in the Libyan civil war have largely stagnated since the popular uprising seeking to oust Gadhafi broke out in February. Rebels, backed by NATO air force bombers, control much of the country's east and pockets in the west. But Gadhafi controls the rest from his stronghold in Tripoli, the capital.

In Friday's final statement following a meeting of the so-called Contact Group on Libya, the nations said: the "Gadhafi regime no longer has any legitimate authority in Libya," and Gadhafi and certain members of his family must go.

The group said it would deal with Libya's main opposition group — the National Transitional Council, or NTC — as "the legitimate governing authority in Libya" until an interim authority is in place.

The recognition of the Libyan opposition as the legitimate government gives foes of Gadhafi a major financial and credibility boost. Diplomatic recognition of the council means that the U.S. will be able to fund the opposition with some of the more than $30 billion in Gahdafi-regime assets that are frozen in American banks.

"The United States views the Gadhafi regime as no longer having any legitimate authority in Libya," said U.S. Secretary of State Hillary Rodham Clinton. "And so I am announcing today that, until an interim authority is in place, the United States will recognize the TNC as the legitimate governing authority for Libya, and we will deal with it on that basis."

In addition to the U.S., the Contact Group on Libya includes members of NATO, the European Union and the Arab League.

Ahead of the meeting, a defiant spokesman for the Libyan government said its members were ready to die in defense of the country's oil against attacks by the rebels and NATO forces. "We will kill, we will die for oil," Moussa Ibrahim said. "Rebels, NATO, we don't care. We will defend our oil to the last drop of blood and we are going to use everything."

A senior U.S. official, speaking on condition of anonymity to discuss private diplomatic conversations with the TNC and the other Contact Group members, said Friday's decision by the Contact Group on Libya indicates strong support for the TNC and that Gadhafi's time is up. The National Transitional Council won international recognition after it said it would abide by its commitments and find a way forward for a truly democratic Libyan government, the official said.

The assurances included upholding the group's international obligations, pursuing a democratic reform process that is both geographically and politically inclusive, and dispersing funds for the benefit of the Libyan people.

The U.S. official said the recognition of TNC as the government of Libya would allow countries to help the opposition access additional funds. However, he stressed that more legal work needs to be done by some countries, including the U.S., and at the United Nations, to fully legalize that step.

The recognition does not mean that the U.S. diplomatic mission in the rebel-held city of Benghazi, Libya, is now an embassy. Titles of staff and names of offices would be decided in the coming days, the official said.

Speaking on the sidelines of Friday's meeting, Italian Foreign Minister Franco Frattini told reporters that "the entire Libyan Contact Group decided to recognize the NTC as the legitimate authority of Libya."

French Foreign Minister Alain Juppe said, "This means that we will be able to unfreeze a certain amount of money belonging to the Libyan state since it is the Transitional National Council which as of now will have this responsibility."

A road map to end the conflict demands that Gadhafi must resign and a cease-fire be declared with a goal for democratic elections, Juppe said. He stressed that military pressure will be kept until Gadhafi steps aside.

Earlier, Turkey's foreign minister urged delegates to find "innovative ways" to support the Libyan opposition. Ahmet Davutoglu suggested the group open lines of credit to meet the Libyan rebels' "urgent need for cash" before the holy Muslim month of Ramadan, which starts next month. Turkey has already started a $200 million credit line, he said.

Davutoglu also stressed the need to increase humanitarian aid Ramadan approaches, warning that ongoing U.N. sanctions are causing suffering among people living under Gadhafi's control.

There have been concerns about whether the initial government would represent the full spectrum of Libyan society, and Human Rights Watch called on the Contact Group on Libya to press the opposition to ensure that civilians are protected in areas where rebels have assumed control.

The right groups said Friday it has documented abuses in four towns — Awaniya, Rayayinah, Zawiyat al-Bagul, and Qawalish — recently captured by rebels in the western mountains, including looting, arson, and beatings of some civilians who remained when government forces withdrew.

"Rebel abuses may pale in comparison with the atrocities by Libyan government forces, but they require immediate attention," said Sarah Leah Whitson, Middle East and North Africa director at Human Rights Watch. "Governments supporting the NATO campaign should push the opposition to protect civilians in areas where rebels have control, especially where some people may support the government."

Turkey, which co-chaired Friday's meeting together with the United Arab Emirates, has called for an immediate cease-fire and providing water, food and fuel to strife-torn cities. It wants NATO to stop targeting ground forces to prevent civilian casualties, HaberTurk television said Friday.

Davutoglu has said Gadhafi could remain in Libya if an agreement is reached, but Gadhafi has refused to step down.