Washington ? Nuclear bombs are likely to be used before the end of the decade if the United States doesn’t do more to stop their spread, a group that advises Senate Democrats said Wednesday.

One key step would be to begin direct talks with North Korea to negotiate an end to its nuclear program, said the National Security Advisory Group, which includes former top officials of the Clinton administration.

Former Defense Secretary William Perry, the group’s chairman, said North Korea could have six to eight nuclear bombs by the end of the year and could have “serial production” next year.

“We must anticipate, given North Korea’s desperate economic condition, that some of the products of their nuclear program will be for sale to the highest bidder and could end up in an American city,” he said.

The Bush administration has said North Korea’s nuclear program was a regional problem and should be resolved with multilateral talks involving South Korea, Japan and China. North Korea wants talks with just the United States.

The advisory group, formed in March, also includes former Secretary of State Madeleine Albright, former national security adviser Sandy Berger, former NATO Supreme Commander Gen. Wesley Clark and former Joint Chiefs chairman Gen. John Shalikashvili.