SEOUL, South Korea — North Korea’s Kim Jong Il had brain surgery after a stroke last month and could have partial paralysis on one side, press reports said yesterday, after the South Korean government said the communist leader remained in control of his country.

Foreign doctors, possibly from China and France, performed the operation after Mr. Kim, 66, collapsed about August 15, the newspapers Dong-a Ilbo and JoongAng Ilbo reported, citing unidentified government officials.

Mr. Kim’s condition has improved and he is not suffering from slurred speech, a disability often associated with a stroke, the reports said.

If Kim were incapacitated, it could have serious implications for international negotiations on North Korea’s nuclear disarmament. The talks recently hit a snag because of a dispute between North Korea and America over how to verify the North’s nuclear programs, and a delay by Washington in its promised removal of North Korea from a list of nations that sponsor terrorism.

“I only hope that any situation happening in DPRK should not affect negatively what has been going on in terms of denuclearization process” Secretary-General Ki-moon told a news conference yesterday at the United Nations, using the initials of North Korea’s official name.

“I’m also concerned deeply by DPRK’s decision to go back to reassembling the nuclear facilities. They must commit to their agreement among the six-party talks for the early realization of the denuclearization process,” said Mr. Ban, who was South Korea’s foreign minister before taking the helm of the U.N. in January 2007.

A South Korean ruling party lawmaker, Lee Cheol-woo, said in a radio interview yesterday that Mr. Kim is “recovering fast,” has “no problem speaking and communicating,” and is “able to stand if assisted.”

The lawmaker, a leader of the parliamentary intelligence committee briefed by the country’s spy agency Wednesday, did not give further details.

However, South Korea’s largest newspaper, Chosun Ilbo, said the stroke had left Kim with “partial paralysis.” It quoted an unidentified senior government official as saying, “I understand that he is suffering inconvenience on the left part of his body.”

South Korea’s main spy agency declined to comment on the reports, only repeating a previous statement that Mr. Kim’s condition had much improved from an unspecified circulatory problem. It also declined to say whether Mr. Kim received surgery.

On Wednesday night, the office of President of South Korea said it had received intelligence reports that Mr. Kim is recovering from a stroke and is still in control of his isolated country.

The North Korean leader was “not seen to be in a serious condition,” a presidential spokesman, Lee Dong-kwan, said in a statement after President Lee convened a security ministers’ meeting to discuss the situation.