UNITED NATIONS, April 13 (Xinhua) -- UN Secretary-General Kofi Annan denounced Thursday rebels in Chad for an attack on the capital of the central African country and urged them to resolve their differences with the authorities through peaceful means.

    "The secretary-general is greatly troubled by the worsening security situation in Chad, resulting from the ongoing fighting between government forces and rebel fighters," UN spokesman Stephanie Dujarric told reporters.

    "He strongly condemns once again any attempts to seize power by force or other unconstitutional means, and appeals to the protagonists to resolve their political differences through peaceful negotiations," Dujarric added.

    The rebel United Front for Change Thursday launched a pre-dawn attack on Ndjamena, Chad's capital, engaged in a fierce battle with the government forces backed by attack helicopters, tanks and heavy weapons. Chadian President Idriss Deby later declared he had fought off the second attempt to overthrow him in a month.

    The Security Council was meeting behind closed doors to discuss the situation in Chad, at the request of the Democratic Republic of Congo, which sits on the 15-nation body. Enditem