GENEVA - Breaking a 12-year stalemate, the U.N.-sponsored Conference on Disarmament finally agreed a work plan on Friday, and diplomats said it would start negotiations on banning production of fissile material for nuclear bombs.

"After more than a decade of deadlock the Conference of Disarmament today took the historic decision to restart work," Britain's ambassador to the arms talks, John Duncan, said in a "tweet" on Twitter.

One diplomat, who asked not to be named, said: "They actually mean business, as opposed to doing what they've been doing for the last 12 years, which is mouth mantras at each other."

The conference will start negotiations on the fissile material cut-off treaty, which would ban production of plutonium and highly-enriched uranium, used to make nuclear bombs.

It will also start discussions on three other areas -- broader nuclear disarmament, "negative assurances" in which countries with nuclear weapons promise not to use them on countries that do not have them, and weaponry in outer space.

The conference will meet next Thursday to decide the arrangements for those negotiations.

Countries can get together one-on-one or in small groups to discuss arms, as Russia and the United States are doing next week in Geneva for another round of their talks on replacing the 1991 Strategic Arms Reduction Treaty (START) to slash Cold-War era stockpiles of nuclear weapons. [ID:nLK960955]

But the 65-member Conference on Disarmament at the United Nations European offices in Geneva, established in 1979, is the world's only multilateral forum on the issue.

"If you want to do anything on arms control, you need the Conference on Disarmament," the diplomat said.

Friday's breakthrough is all the more remarkable as the emerging agreement was threatened on Tuesday when North Korea -- angered by criticism of its latest nuclear test -- said it might withhold support.