Washington  - Incoming US President Barack Obama signalled a "new era" of transparency, accountability and rule of law in his administration, signing a series of ethics-related directives on his first full day in the White House Wednesday.

"Transparency and the rule of law will be the touchstones of this presidency," Obama said during a signing ceremony, which also included the swearing-in of Obama's senior White House staff.

The directives were part of a flurry of activity on Obama's first day in office. Controversial US military tribunals at Guantanamo Bay, Cuba were suspended for 120 days. Obama also planned meetings with his top economic and military advisers later Wednesday.

Obama said he hoped his directives would help "restore trust" in the US government. Opinion polls have shown dropping public confidence in government, with departing president George W Bush leaving with one of the lowest approval ratings in recent times.

Among his ethics reforms, Obama tightened lobbying regulations on current and former White House officials, including barring staff members from lobbying the administration if they leave their White House job, calling for a "clean break from business as usual."

Obama also called for a pay freeze for senior White House staff, noting that families around the country were also "tightening their belts" in response to a serious recession afflicting the world's largest economy.

Obama promised to open up more of his administration's documents to public and media scrutiny, though he reserved the right to withhold information sensitive to national security and privacy.

"For a long time now there's been too much secrecy in this city," Obama said in an implicit criticism of the Bush administration, which battled regularly with the media over the release of documents. "That era is now over."

Former vice president Dick Cheney was notorious for his disdain of the press. Early in the administration Cheney withheld documents related to an energy taskforce led by the vice president.

The Bush administration also came under fire for secret surveillance measures in the war on terrorism, including warrantless wiretaps on US citizens' conversations with people abroad that were suspected of terrorism. The programme was eventually revealed by The New York Times over stiff objections from the White House.

"The mere fact that you have the legal power to keep something secret does not mean you should always use it," Obama said, adding he would consult with his attorney general and White House counsel on any documents he plans to keep secret. (dpa)