BEIJING (AP) – North Korea was under pressure Sunday to take action after failing to meet a deadline for shutting its nuclear reactor, with Washington calling for Pyongyang to allow nuclear inspectors back into the country.

America also sent a message to Pyongyang through its embassy in Beijing urging it to act on its promises according to the nuclear agreement, Assistant Secretary of State Hill, the chief American negotiator, said Sunday.

North Korea had until Saturday to shut down its Yongbyon reactor and allow inspectors from the U.N.’s nuclear watchdog, the International Atomic Energy Agency, to verify and seal the facility.

In return, it was to have received 50,000 tons of heavy fuel oil under an agreement with America and four other governments to abandon its nuclear programs.

Saturday’s missed deadline marked the latest setback in an agreement, that when reached in February offered the prospect of disarming the world’s newest nuclear power. North Korea tested a nuclear bomb in October.

Mr. Hill said the American note to North Korea, delivered Saturday, urged Pyongyang to fulfill its commitments and invite U.N. nuclear inspectors into the country.

“It’s their turn now. The ball’s in their court,” he said in Beijing, ahead of his departure for Washington later Sunday.

“We’re not happy that the DPRK essentially has missed this very important deadline,” Hill said, using the official name of the Democratic People’s Republic of Korea. “We’re obviously going to be watching the situation very closely in the coming days.”

Mr. Hill said America was prepared “to hold on for a few more days” after talks Saturday with his Chinese counterpart, Wu Dawei, who asked America for patience.

Washington, however, has held back from criticizing Pyongyang for missing the 60-day deadline, but called on the North to show it remained committed to giving up its nuclear weapons.

“It remains for the DPRK to realize fully its commitments under the February 13 agreement by inviting back the IAEA immediately to begin shutting and sealing the Yongbyon nuclear facility,” American State Department spokesman Sean McCormack said.

North Korea kicked IAEA inspectors out and quit the Nuclear Nonproliferation Treaty in December 2002.

“It is time now for the DPRK to make its move so that all of us can move forward,” Mr. McCormack said.

The timetable for the North’s disarmament was tripped up by a dispute over North Korean deposits frozen in a tiny Macau bank, which was blacklisted by Washington for allegedly abetting money-laundering and counterfeiting.

North Korea refused to make any move until the funds issue was resolved, but the matter – which was supposed to have been resolved in mid-March – dragged on until this past week.

Pyongyang has not responded to the latest diplomatic maneuvering. The North Korean capital was consumed by preparations for Sunday’s birthday of the communist nation’s late founder, Kim Il Sung.

Mr. Hill has said he expected negotiators for the six countries involved – South Korea, Japan and Russia as well as America, North Korea and China – would likely meet again before the end of the month to discuss the next phases in disarming North Korea.