Prime Minister Stephen Harper says that while Canadian firms face still significant risks in Colombia, the government here has made big strides to improve security.

Harper was in the Colombian capital today to meet President Juan Manuel Santos days before a free-trade deal between the two countries kicks in.

That agreement has been criticized by the opposition New Democrats and activist groups over Colombia's dubious human rights record.

It is alleged the Colombian government is linked to violent paramilitary squads and there have been a number of murders and kidnappings of union leaders and journalists over the years.

Lately, oil and gas companies have also been targeted.

Colombia's largest Marxist guerrilla group, the Revolutionary Armed Forces of Colombia, or FARC, has stepped up attacks on the country's oil sector in recent months, including a recent attack on a Canadian company.

The attacks have sparked a debate over who should provide security, the government or the oil companies.

On Sunday, the FARC was blamed for blowing up drilling equipment and burning 1,000 barrels of crude at a field near the Venezuelan border operated by the Canadian firm Alange Energy.

The head of an association of multinational oil companies that operate in Colombia told a local radio station today that it is up to the government to protect workers and infrastructure from rebel attacks.

But Colombia's defence minister says it is impossible for the military to guard every oil installation and it is up to the companies to hire their own security forces.