Libya's interim government says it has gained control of a string of desert cities in the country's deep south including the oasis town of Sabha, which had been one of former leader Moammar Gadhafi's few remaining strongholds.

The National Transitional Council said Thursday it also controls Jufra – northeast of Sabha – and the nearby towns of Sokna, Waddan and Houn.

Provisional authority fighters are still engaged in fierce battles for two much larger loyalist bastions in the north – Bani Walid and Mr. Gadhafi's hometown of Sirte. NTC forces have been facing stiff resistance from armed fighters in both towns.

Meanwhile, the International Atomic Energy Agency confirmed that Mr. Gadhafi's government had stored uranium near Sabha that was left over from the former regime's nuclear program. The U. N. nuclear watchdog said the uranium is being stored in drums at the site “which Libya previously declared to the IAEA.”

Earlier Thursday, the U.S. reopened its embassy in the capital, Tripoli, months after it closed down during the fighting to oust Mr. Gadhafi from power.

Ambassador Gene Cretz said the upcoming period will be critical as Libyans “lay the groundwork for a pluralistic democracy” that respects the rights of all its citizens. He said the United States and the international community “are ready to help in any way we can.”

The ceremony occurred on the same day that Tunisia sentenced former Libyan Prime Minister Baghdadi Mahmudi to six months in prison for illegally entering the country. Tunisian authorities say they arrested the Gadhafi-era official in a border region late Wednesday.

In another development, NATO announced it is extending operations in Libya for another three months. Chief Anders Fogh Rasmussen said Wednesday the alliance is determined to continue its mission “for as long as necessary.”