GENEVA, Feb 22 (Reuters) - The United Nations' top human rights official called on Chad on Friday to investigate the killing of civilians during recent fighting and voiced concern at the "abduction and detention" of several opposition leaders.

Rebels, who denounce President Idriss Deby's 18-year rule as corrupt and dictatorial, attacked N'Djamena in early February. The fighting killed 160 people and since then activists say several opposition leaders have disappeared.

"We remain concerned about reports of killings of large numbers of civilians during the fighting and call upon the government of Chad to fully investigate these allegations and hold those responsible to account," said a spokesman for Louise Arbour, the U.N. High Commissioner for Human Rights.

While recognising that the government had faced a major crisis with fighting in the heart of the capital, her office said it was essential that detentions meet international legal standards and that detainees' fundamental rights be protected.

The scope of a Feb. 15 presidential decree declaring a nationwide state of emergency was also raised as a concern. That degree authorised house searches, controls on the press, limits on movement of people and vehicles and banned most meetings, spokesman Rupert Colville told a news briefing in Geneva.

"We call on the government of Chad to respect fundamental human rights and freedoms during the period of the state of emergency which we hope will be as brief as possible," he said.

Pan-African human rights organisation RADDHO said in a statement on Tuesday that Chadian opposition leaders and rights campaigners had been arbitrarily detained or forced into hiding. But Chad's interior minister denied that soldiers had visited the houses of human rights activists to arrest them. (Reporting by Stephanie Nebehay; Editing by Matthew Tostevin)

AlertNet news is provided by