U.N. rights chief urges Obama to prosecute torturers

* Navi Pillay welcomes U.S. joining U.N. rights forum

* Urges United States to prosecute those guilty of torture

GENEVA, May 14 (Reuters) - The U.N. High Commissioner for Human Rights on Thursday welcomed the election of the United States to the top United Nations rights forum and urged it to prosecute those accused of torture and other abuses.

Navi Pillay said Washington should investigate all U.S. renditions of terrorism suspects and ensure any interrogators who mistreated them are brought to justice for violating an international ban on torture.

Her appeal, in an opinion piece in the International Herald Tribune, came a day after President Barack Obama said he would fight the release of dozens of photographs showing the abuse of terrorism suspects over concern the images could ignite a backlash against U.S. troops deployed abroad.

The United States' election on Tuesday to the United Nations Human Rights Council could help the cause of human rights and America's standing in the international community, Pillay said.

She described Washington's decision to seek a seat for the first time at the 47-member forum as a "welcome step in restoring international trust in U.S. support for human rights".

"Although much more needs to be done, President Obama's determination to resolve the untenable situation of detainees at Guantanamo Bay, ban CIA prisons and implement the prohibition on torture in compliance with international standards is highly welcome," the former U.N. war crimes judge said.

She was referring to executive orders signed by Obama in his first days in office in January to close the Guantanamo military prison in Cuba and overseas CIA jails.

"The U.S. should also shed light into the still opaque areas that surround capture, interrogation methods, rendition and detention conditions of those alleged to have been involved in terrorism, and ensure that perpetrators of torture and abuse are held to account," Pillay said.

Under President George W. Bush, the United States confirmed it had used "rendition" to apprehend terrorism suspects around the world and deliver them for interrogation in third countries.

It also acknowledged that the CIA had run secret interrogation centres abroad, but denied employing torture.

The system was put in place after the Sept. 11, 2001 attacks in the United States, which killed nearly 3,000 people.

U.N. human rights investigators launched a global inquiry into secret detentions last March and said they would not relax scrutiny of U.S. counter-terrorism policies under Obama.

The investigation will look at CIA "rendition" flights that secretly transferred suspects for interrogation, mainly in North Africa and the Middle East, but will also investigate countries' use of torture in secret prisons anywhere in the world.

Martin Scheinin, U.N. special rapporteur on protecting human rights while countering terrorism, and Manfred Nowak, the U.N. investigator on torture worldwide, are conducting the investigation. The independent experts report to the U.N. Human Rights Council. (Editing by Janet Lawrence)