By Abdi Sheikh

MOGADISHU (Reuters) - Islamist rebels firing rocket-propelled grenades briefly seized a major police base in the heart of Somalia's capital, residents said on Friday, raising even more doubt over prospects for rare peace talks.

Witnesses said the insurgents took control of the compound late on Thursday and torched at least one government "technical" -- a truck mounted with a heavy gun -- before retreating as reinforcements arrived.

"The fighting was hideous, terrifying," one resident, Hawa Abdi, told independent local broadcaster Shabelle by telephone from Mogadishu's central Waberi district.

"I thought it would smash the walls of my concrete home."

Islamist spokesman Abdirahim Issa Adow told Reuters their forces killed eight policemen, while two of their fighters died.

Police spokesman Abdullahi Omar Shasha said only two policemen were killed, and four militants had been captured.

"They killed two of our officers and burnt three public vehicles that were parked near the base," Shasha said.

The attack in a heavily guarded area that neighbours the city's air and sea ports followed a flare-up of fighting between the insurgents and allied Somali-Ethiopian troops in which at least 19 people were killed.

There were also clashes between security forces and rebels on Friday in the northern Puntland region, witnesses said.

DEAD BODIES

"I saw the bodies of three dead civilians lying in different places and three injured policemen being carried in a car after the fighting stooped," local waiter Saad Muse told Reuters.

The violence cast a pall over tentative, U.N.-brokered peace talks between Somalia's interim government and opposition exiles that were due to begin on Saturday in Djibouti.

The militants behind near-daily ambushes and roadside bombs are the remnants of an Islamist movement that was ous