The United States is offering technical assistance to Spain to clean up land contaminated by radiation from undetonated nuclear bombs that accidentally fell on the area in 1966, the US State Department announced Saturday.

The Spanish and US governments have not yet reached an agreement on the cleanup.

At the request of the Spanish government, an American technical team led by the US Energy Department traveled to the southeastern Spanish town of Palomares in February 2011 to offer advice for the remediation plan.

"No final decision has been reached regarding cleanup of the site," the State Department said in a statement on its website.

On January 17, 1966, a US B-52 bomber carrying four nuclear bombs collided with a KC-135 tanker during mid-air refueling off the coast of Spain. In addition to killing seven crew members on the airplanes, three hydrogen bombs fell to the ground near Palomares and one fell into the Mediterranean Sea.

The non-nuclear explosives on two of the bombs that hit the ground detonated, spreading seven pounds of plutonium over a 200 hectares (490 acres). The bomb that fell into the sea was recovered intact after a search by the US Navy.

"In 1966, we worked closely with Spain to remediate the accident site, and have collaborated with Spanish authorities for more than 40 years to monitor the site and the health of local inhabitants," the State Department statement Saturday said.

Spanish Foreign Minister Jose Manuel Garcia-Margallo spoke with US State Department Secretary Hillary Clinton about the remediation this week during the Munich Security Conference in Germany, according to the Spanish newspaper Herald of Aragon.

Clinton is "personally committed" to resolving the contamination issue, Garcia-Margallo told the Spanish news media.