Libya has handed over a design for nuclear weapons to the United Nations nuclear agency. The drawing provides the first hard evidence that Libya was planning to build nuclear arms.

A spokesman for the U.N. nuclear watchdog agency said Friday the drawings are sealed and secure, but gave no details about what the designs contain.

The drawings are now in Washington. U.S. experts will open them in the presence of U.N. officials, to determine how advanced Libya's plans actually were.

The U.N. nuclear agency, which is overseeing Libya's disarmament, has said Libya was years away from developing a nuclear weapon.

U.S. and British experts in charge of removing and destroying Libya's arms capabilities believe Libya was making an aggressive push toward gaining the knowledge and materials to build nuclear weapons.

Last month, Libyan President Muammar Gaddafi pledged to abandon his country's weapons of mass destruction campaign, hoping to bring an end to U.S. economic sanctions that have been in place since the mid 1980s.

The United States banned Libyan oil imports in 1982 and expanded those sanctions in 1986 to ban all import and export activity between the two countries.

U.S. and Libyan diplomatic ties deteriorated further after the U.S. suspected Libyan involvement in the 1988 bombing of Pan Am flight 103, which blew up over Lockerbie, Scotland killing all 270 people on board.

In August, Libya admitted responsibility for the plane crash and moved to make more than $2.5 billion in reparations to the families of those killed, on the condition that U.S. and U.N. sanctions are lifted.

Last month, in a move to speed up improved relations with the U.S., Tripoli invited arms inspectors to come into Libya and dismantle and remove any nuclear, chemical or biological weapons materials.

Officials from the International Atomic Energy Agency and a team of U.S. and British experts have been in Libya since Tuesday. In addition to finding designs for weapons, they also hope to also uncover any weapons components.