A new U.N. Security Council resolution aimed at punishing North Korea for conducting its third nuclear test last month is expected to call for sanctions on the North's uranium-related transactions for the first time, a Seoul diplomatic source said Wednesday.

After weeks of bilateral consultations, the United States and the North's last-remaining ally China agreed to the draft resolution, which also calls for mandatory inspections of North Korean ships and planes suspected of carrying banned items, including luxury goods, the source said on the condition of anonymity.

It will also make it difficult for North Korea to move in and out "bulk cash," in an effort to squeeze the North Korean elite's access to hard currency, the source said.

In particular, the proposed resolution will include the North's "uranium enrichment program" for the first time and call for an explicit ban of uranium-related transactions, according to the source with knowledge of the text.

North Korea conducted its third nuclear test on Feb. 12, defying international warnings of tougher sanctions and raising the prospect that Pyongyang might be a step closer to a workable long-range nuclear missile.

So far, it has remained unclear whether North Korea used plutonium or uranium to fuel last month's test and monitoring for signs of radioactive seepage from the North has failed to answer the question.

The North claims its uranium enrichment program is for peaceful energy development, but outside experts believe that it would give the country a new source of fission material to make atomic bombs, in addition to its widely known plutonium-based nuclear weapons program.

"In terms of responding to North Korea's third nuclear test, this resolution includes tougher sanctions imposed by the Security Council against the North, compared with previous resolutions," the source said.

Citing the text of the draft resolution, the source said it aims to focus on strengthening sanctions against North Korea's financial activities, cargo and diplomats, which are designed to deter the North from further developing its nuclear and missile programs.

The draft requires all U.N. states to inspect any North Korean cargo believed to contain "military supplies, luxury goods and other banned items," according to the source, adding it makes clear what "luxury goods" are by listing them as jewelry and yachts.

The draft also warned of "further significant measures" if North Korea conducts another nuclear or missile test, the source said.

In New York, U.S. Ambassador to the United Nations Susan Rice said the envisioned resolution would significantly expand sanctions against Pyongyang.

It would subject North Korea "to some of the toughest sanctions imposed by the United Nations," she told reporters after a closed-door session of the 15-member council.

"For the first time ever, this resolution targets the illicit activities of North Korean diplomatic personnel, North Korean banking relationships and illicit transfers of bulk cash," Rice said.

In response to the proposed U.N. sanctions and ongoing Seoul-Washington joint military drills, the North's military threatened to scrap the Korean War cease-fire.

Kim Yong-chol, a hard-line North Korean general suspected of involvement in a series of provocations against the South, read the statement on state TV, saying the North "will completely declare invalid" the Armistice Agreement that ended the 1950-53 Korean War.

The North also said it will cut off a military phone line at the truce village of Panmunjom. (Yonhap News)