Two explosions rocked a largely Christian city in the southern Philippines today, killing 14 people and wounding about 50, in what police said could be attacks by Muslim extremists.

The bombings in General Santos city - some 215 miles from where US forces were holding counter terrorism exercises with their Filipino counterparts - were the bloodiest in the mainly Christian country since suspected Muslim extremists killed 14 and wounded over 100 in a wave of bombings in the capital Manila in December 2000.

"We have leads and suspects. Within a few hours or days we will get them," regional police chief Colonel Bartolome Baluyot told Reuters by phone.

He refused to name the suspects but said they were from the same group blamed for two bomb attacks in General Santos last year, which killed four people.

Police had blamed last year's attacks on Muslim guerrillas fighting for an Islamic state in the south of the country.

In Sunday's attacks, a home-made bomb left in a parked pedicab exploded as shoppers waited for rides home outside a shopping mall.

Ten minutes later, another bomb thrown by unidentified attackers exploded near a residential compound.

Police said they suspected the bomb-throwers had also planted the first bomb.

The victims were shoppers, public transport drivers and street hawkers gathered outside the mall, as well as children.

"I think there may be more dead because many of the injured are in serious condition," Baluyot said. More than half of the injured were in serious condition in hospitals, he added.

After the explosions, a man who said he represented the Muslim Abu Sayyaf guerrilla group, which operates in the country's south and is linked by the United States to Saudi-born militant Osama bin Laden's al Qaeda network, called local RMN radio and claimed responsibility for the blasts.

The man, who identified himself as Abu Muslim al Ghazi, called the RMN radio and said "we did it," station manager Elmer Ubaldo told Reuters. He said the man had in the past called the station saying he was head of a special operations unit of the Abu Sayyaf.

Baluyot said he did not know how credible the call was, but investigators were looking into the possible involvement of Muslim radicals.

"We are looking into that. That is one possibility," he said.

Prior to the explosions, General Santos had been swamped with rumours, circulated through text messages on mobile phones, that extremist groups had planted 18 bombs across the city that were due to be exploded on Sunday.

The explosions occurred just three days after a Philippine court sentenced Fathur Roman al-Ghozi, an Indonesian national with alleged links to al Qaeda, to a jail term of up to 12 years for alleged possession of explosives.

Al-Ghozzi has admitted to prosecutors he is a member of the clandestine Jemaah Islamiah group, which is alleged to have links with al Qaeda, but denied knowing Osama bin Laden.

General Santos lies 1,000 km (600 miles) south of Manila and 350 km (about 215 miles) east of Basilan island, where US special forces are training Filipino troops in counter terrorism to help them defeat Muslim Abu Sayyaf guerrillas holding a US missionary couple hostage for almost 11 months.

The United States has listed the Abu Sayyaf as a supporter of al Qaeda, prime suspect in the September 11 attacks on New York and Washington.

General Santos, a city of 800,000 people on the main southern island of Mindanao, was the same city where police arrested three Filipinos suspected of links with the al Qaeda network and confiscated a tonne of explosives from them in January.

The bulk of the nation's five million Muslim minority lives in southern Philippines.

Police around the country have been on heightened alert since last month when 23 home-made bombs were found by police in public places in several Philippine cities. None of the bombs exploded.

A previously unknown group calling itself the Indigenous People's Federal Army, demanding federal states for Muslims and other ethnic groups, claimed that it planted most of the bombs.

Besides the Abu Sayyaf, the government is fighting other Muslim groups demanding an Islamic state in the south.