The Colombian defence ministry says Venezuelan military jets crossed several kilometres into Colombian airspace.

Air force radars "detected the entry to Colombian territory of two Venezuelan military aircraft in the Alta Guajira zone" on the northern border with Venezuela on Saturday afternoon, the ministry said in a statement.

The planes entered Colombia for nearly 3km and then flew over an army unit, it said. The ministry did not describe the type of aircraft detected.

Colombia's government will formally protest and seek an explanation from Venezuela for the airspace violation, Colombian President Juan Manuel Santos said.

"I have ordered the foreign ministry and defence ministry to present a formal protest tomorrow to Venezuela for violation of our airspace," he said on Twitter.

Delcy Rodriguez, Venezuela's foreign minister, said there was no evidence of any violation of Colombian airspace.

"We're concerned about the systemic tendency of the Colombian government to invent non-existent incidents," she wrote on Twitter.

Escalating row

Colombia and Venezuela have been in an escalating row since Venezuelan President Nicolas Maduro closed part of their shared border on August 19, blaming Colombian paramilitaries for an attack on a Venezuelan anti-smuggling patrol.

Maduro closed several major border crossings and deported 1,300 Colombians last month in what he said was a crackdown on smuggling and crime.

Venezuela has deported about 1,500 Colombians living in Venezuela since the crisis began, and more than 18,500 others have fled in fear, the UN said.

The foreign ministers of Colombia and Venezuela met in Ecuador on Saturday in a failed attempt to resolve their differences [Reuters]

Colombians were forced in many cases to cross rivers and bridges with their belongings on their backs.

Santos has blamed the border crisis on Maduro and said last week that Venezuela's socialist revolution had failed.

Maduro, for his part, says he is protecting his country from criminals who smuggle everything from petrol to flour across the border.

'Attack on economy'

Maduro accused Colombia of waging an "attack on Venezuela's economy", a reference to the rampant smuggling of heavily subsidised goods out of the oil-rich but shortage-hit country.

The foreign ministers of Colombia and Venezuela met in Ecuador on Saturday in an attempt to resolve their differences.

While they agreed to renew diplomatic contacts after ambassadors were withdrawn, they failed to agree on a meeting between the two country's presidents.

In 2010, troops were rushed to the border after the Colombian president accused Venezuela of giving safe haven to leftist Colombian rebels.

The crisis was defused when Santos took office.

Maduro says he is protecting Venezuela from criminals who ply their smuggling business across the border with Colombia [EPA]

Source: Agencies