By Jason Webb

Bogota - A young woman was killed and three Americans and a German were among 72 injured in a Saturday night grenade attack on two popular pubs in Colombia's capital Bogota, police said on Sunday.

Police arrested a man who fled the scene, and said they suspected he was a member of the Revolutionary Armed Forces of Colombia, a Marxist rebel group known by the Spanish initials FARC. But they were also investigating whether the motive for the attack was personal and not political.

A grenade ripped through the crowded terrace of the Bogota Beer Company pub at about 10.30pm, detonating an outside gas heater, police said.

Another grenade exploded at the adjacent Palos de Moguer pub, on the edge of a block lined with busy bars and restaurants packed with people enjoying a Saturday night out in Bogota's upmarket entertainment district.

An unidentified woman in her twenties was killed and 72 injured by the force of the blasts, by shrapnel and burning gas, police said.

Vance Vogli, a 43-year-old American Airlines pilot who was hurt in a leg, was among three United States citizens wounded at the pubs, which are popular with wealthy young Bogotanos and foreigners. A German was also injured.

"In Colombia the guerrillas have no ideals. There is a damned mix of terrorism, fed by drugs," President Alvaro Uribe, told reporters in the city of Barranquilla.

Uribe, a close US ally, has overseen a military build-up to hunt down about 20 000 Marxist rebels hiding in Colombia's anarchic, poor countryside. The guerrillas, like illegal far-right groups, draw much of their funding from cocaine.

"There is only one way to deal with terrorism: perseverance in defeating it, with sacrifices, overcoming obstacles," said the president, whose father was killed resisting a kidnap attempt by leftist guerrillas in the early 1980s.

"I heard an explosion, and then another one. I just tried to help people who were hurt," injured street vendor Arturo Vasquez said shortly after the blast, as police cordoned off the area.

He had large blood stains on his jeans, and more blood stained a cloth bag slung over his shoulder.

While thousands of people are killed every year in a four-decade-old war involving leftist guerrillas and far-right paramilitary outlaws, attacks on civilian targets in the capital are relatively rare despite rebel threats to bring the fighting to the cities.

Visitors to Bogota often remark on the crowds packing restaurants and shopping malls in the capital of a war-torn nation. Bomb sniffing dogs and armed guards are often the only reminder of a conflict which is endemic in many rural areas.

A car bomb killed six people in a grimy Bogota commercial district in October, and police investigated both leftist rebels and far-right paramilitaries. Authorities blamed the FARC for a huge bomb that killed 36 people at the city's exclusive Nogal Club in February.

Repairs on the bars started immediately and their owners said they would reopen on Sunday night with a protest concert.