By Stephen Cviic BBC News

At least 20 people were killed and about 150 were injured in the car-bomb attack on a club used by politicians and diplomats.

Left-wing rebel groups are trying to bring their campaign from the countryside into the cities

It is not yet known who carried out the attack, although the authorities suspect rebels of the Revolutionary Armed Forces of Colombia (FARC).

President Alvaro Uribe said the bombing showed that the whole world needed to be tougher on people he described as terrorists.

Colombia's cities may be violent places, but most urban killings have until now had little to do with the four-decade-long civil war.

The last big bombing campaign in the early 1990s was carried out by the Medellin drug cartel.

Now, though, it is left-wing rebel groups who are trying to bring their campaign from the countryside into the cities.

And if this attack was the work of the FARC, it was an attempt to show Colombia's elite that they are targets.

President's priorities

Last year, Colombians elected Mr Uribe to be president. He is a right-winger whose fierce anti-terrorist rhetoric chimed well with the feelings of most ordinary people and with the direction of policy in the United States.

President Uribe wants to show the rest of the world that Colombia is not a failed state riddled with conflict, but a fully-fledged democracy under attack from insurgents

Mr Uribe says he wants peace - eventually.

But in order to get there he has vowed to crush the FARC and the other smaller left-wing guerrilla group, the ELN.

Washington is giving more financial and military support, and significantly this help is no longer confined to trying to eradicate the production of illegal drugs.

US special forces are training the Colombian army in counter-insurgency.

President Uribe wants to show the rest of the world that Colombia is not a failed state riddled with conflict, but a fully-fledged democracy under attack from insurgents.

After Friday's bombing in Bogota, he said some foreign countries had been too soft on Colombia's armed groups, and that his country needed technical and financial resources to help defeat them.

It is too early to say how the president is doing.

The numbers of people killed in political violence fell last year, and it was thought that the FARC had been forced on to the back foot by army offensives.

But the latest attack shows they may be launching a campaign against high-profile urban targets.