MercoPress. South Atlantic News Agency

Colombia's under alert.

Security has been stepped up in Colombia ahead of President Alvaro Uribe's inauguration for a second term in office today.

Some 30,000 soldiers and police patrolled the streets, while 17 helicopters kept watch from over Bogota, a city of nearly 7 million people. Soldiers armed with assault rifles and armored vehicles also stood guard at checkpoints across the capital searching vehicles for explosives and weapons.

Presidents and officials from more than 20 countries are attending Monday's inauguration ceremony.

Meanwhile, the government wasn't taking any chances with Monday's inauguration, rebels of the Revolutionary Armed Forces of Colombia (Farc) launched of the 2002 mortar attack that terrified visiting dignitaries and killed 21 people in a slum near the presidential palace..

Bogota's press says the guerrillas want to show the president that despite four years of US-backed army offensives they are as strong as ever.

In the lead-up to the second inauguration, Farc have already detonated two car bombs, ambushed an army patrol and engaged in isolated attacks.

Security in the major cities is tight, and the police and army are on a high state of alert.

Whilst it is believed that Bogota will be the primary target for the rebels, the city of Cali has already seen a car bomb detonated outside a police station, out correspondent adds.

President Alvaro Uribe has pursued a tough security policy against rebel groups.