The chairman of a commission investigating the 11 September attacks says he is prepared to subpoena some documents relevant to his probe from the White House, if it fails to turn them over within weeks, The New York Times reported in its Sunday edition.

Former New Jersey governor Thomas Kean told the newspaper the White House was continuing to withhold several highly classified intelligence documents.

Kean also said in an interview on Friday that he believed the bipartisan 10-member commission would soon be forced to issue subpoenas to other executive branch agencies because of continuing delays by the Bush administration in providing documents and other evidence needed by the panel, according to the report.

"Any document that has to do with this investigation cannot be beyond our reach," Kean is quoted by The Times as saying.

The remarks were his first explicit public warning to the White House that it risked a subpoena and a politically damaging courtroom showdown with the commission over access to the documents, including Oval Office intelligence reports that reached President Bush's desk in the weeks before the 11 September attacks, the paper said.

"I will not stand for it," Kean said. "That means that we will use every tool at our command to get hold of every document."

He said that while he had not directly threatened a subpoena in his recent conversations with the White House legal counsel, Alberto Gonzales, "it's always on the table, because they know that Congress in their wisdom gave us the power to subpoena, to use it if necessary," according to the report.

White House spokeswoman Ashley Snee said that the White House believed it was being fully cooperative with the commission. The Times quotes Snee as saying the White House hoped to meet all of the panel's demands for documents.