President Bush refused to lift U.S. sanctions against Libya (search) on Monday, saying Moammar Gadhafi (search) must take concrete steps to fulfill a pledge to scrap his chemical and nuclear weapons programs.

Bush said he was keeping in force a declaration of national emergency first issued by President Reagan in 1986 when the United States blocked Libyan assets in the United States, accusing Gadhafi's regime of sponsoring terrorism.

The U.S. sanctions have denied Libya access to hundreds of millions of dollars in property and bank assets, according to U.S. estimates.

Bush, in a written notice, said Libya's promise last month to abandon weapons of mass destruction marked "an important and welcome step toward addressing the concerns of the world community."

"As Libya takes tangible steps to address those concerns, the United States will in turn take reciprocal tangible steps to recognize Libya's progress," Bush said. "Libya's agreement marks the beginning of a process of rejoining the community of nations, but its declaration of December 19, 2003, must be followed by verification of concrete steps."

The declaration of national emergency has been renewed every year since 1986.

Bush said that "the crisis between the United States and Libya that led to the declaration of a national emergency ... has not been fully resolved, although there have been some positive developments."

The United States abstained from voting last year when the United Nations Security Council (search) acted to end U.N. sanctions against Libya. The U.N. acted after Libya agreed to compensate families of the victims of the Pan Am 103 (search) bombing and to take responsibility for the actions of Libyan officials in the bombing.

Explaining Monday's decision to keep U.S. sanctions in tact, Bush said the United States has "serious concerns" about other Libyan policies and actions, including Libya's pursuit of weapons of mass destruction, Libya's role with respect to terrorism, and Libya's poor human rights record.

The White House noted that while Bush is keeping the sanctions in place, he has the power to modify or end the declaration of national emergency whenever he believes it appropriate.