George W Bush has chosen Tom Kean to chair the 11 September commission following the sudden resignation of former Secretary of State Henry Kissinger last week.

Mr Bush praised Mr Kean - a former governor of New Jersey - for his "integrity, fairness and good judgement", in a prepared statement announcing the appointment.

The commission charged with investigating events leading up to last year's terror attacks on the United States has been plagued with difficulties even before beginning its work.

Mr Kean is now a university president

Mr Kissinger resigned on Friday - 16 days after being appointed - over potential conflicts of interest with his position as head of a consulting firm.

Just two days earlier former US Senator George Mitchell had resigned as deputy chairman.

There have also been disputes about the commission's organisation and authority to compel witnesses to testify.

Conflict-of-interest concerns

Mr Kissinger had been criticised for refusing to release the names of clients at his consulting firm.

The Kissinger episode was enormously embarrassing for Mr Bush, raising questions about why possible conflicts of interest were not investigated before his appointment, the BBC's Tom Carver in Washington says.

3,000 died in the attacks

Mr Kissinger's appointment drew controversy when it was announced.

Although he is one of the United States' best known statesmen, he was seen by some as tainted not only by his business dealings, but also by his involvement in murky periods of the country's history.

Mr Kean, who was governor of New Jersey from 1982 to 1990, is now president of Drew University.

Senator Mitchell - who resigned because the job would conflict with his responsibilities to his law firm - is being replaced by another former politician, the Democrat Lee Hamilton.

Commission takes shape

The Speaker of the House of Representatives, Dennis Hastert, has named former Illinois Governor Jim Thompson and Fred Fielding, a former White House counsel, to the commission.

Senate Republican leader Trent Lott has selected former Senator Slade Gorton for the position. He has not yet named a second member.

The commission has been given 18 months to examine issues such as aviation security and border problems, along with intelligence failures.

It was given a broad mandate, building on the limited joint inquiry conducted by the House of Representatives and Senate intelligence committees.

The commission was initially opposed by the White House but was set up following pressure from families of those who lost their lives in the attacks.