President Donald Trump has confirmed reports he authorised the CIA to conduct covert operations inside Venezuela - and said he was considering strikes targeting drug cartels there.

US forces have already conducted at least five strikes on suspected drug-carrying boats in the Caribbean in recent weeks, killing 27 people. UN-appointed human rights experts have described the raids as 'extrajudicial executions'.

Speaking in the Oval Office, Trump said the US 'is looking at land' as it considers further strikes in the region.

Trump has sought to increase pressure on President Nicolas Maduro, who the US and others do not recognise as Venezuela's rightful leader following disputed elections.

The increased US military presence in the region has raised fears in Caracas of a possible attack. According to the New York Times, Trump's authorisation would allow the CIA to carry out operations in Venezuela unilaterally or as part of any wider US military activity.

Speaking to reporters, Trump was asked about the motives for the CIA action: 'I authorised for two reasons really,' he stated, 'They [Venezuela] have emptied their prisons into the United States... And the other thing are drugs.'

While Maduro has not directly commented on the CIA authorisation, Vice-President Delcy Rodriguez has issued a defiant warning against US aggression.

The strikes are part of a larger military effort to pressure Maduro's government, which has included positioning significant air and naval assets in the region as well as around 4,000 troops. The US has alleged Maduro is connected to high-ranking officials involved in drug trafficking, a claim opposed by Maduro's administration.