The United States has stopped annual compensation payments it has made to Spain for a 1966 accident in which two nuclear bombs fell on a village, a Spanish government source said Monday.

They said a bilateral agreement in force since the accident "expired" last year, the source at the ministry of science and innovation said.

In January 1966, a US Air Force B-52 bomber collided with a KC-135 tanker during a midair refueling over southern Spain.

Two of the four hydrogen bombs detonated near the small town of Palomares, dispersing radioactive plutonium.

Since then Washington has provided an annual compensation to Spain to monitor pollution levels and perform blood tests on more than 1,000 residents.

The Spanish newspaper El Pais said Monday the amount was 403,000 dollars (314,00 euros) per year. It added that the issue was discussed during a visit to Spain in May by US Vice President Joe Biden.

El Pais said "traces of plutonium and americium remain in about 20 hectares" and in 2007 Washington and Madrid signed an agreement under which the United States agreed to pay for the cleanup of the area.

Now the Spanish government "wants Washington to agree to remove the plutonium" as Spain has no appropriate disposal site, the newspaper said.

The US Department of Energy said in a statement on its website Monday that its "cost-sharing arrangement with the Kingdom of Spain, begun in 1966, ended in" financial year 2008.

"The final radiological survey was completed in 2009 and received a positive review by the International Atomic Energy Agency. Plans for final remediation are in preparation in 2010."