Venezuela has freed at least two jailed Americans as it seeks to improve relations with the Biden administration, which is looking to undercut support for Russia in Latin America.

A non-governmental group that tracks arbitrary detentions and another person familiar with the matter confirmed to the AP news agency on Tuesday night the release of Gustavo Cardenas, one of six oil executives jailed for more than four years.

The other was a Cuban American detained on unrelated charges, Reuters news agency cited people familiar with the matter.

The move follows a secret weekend visit to Venezuela by senior Biden administration officials, including the top White House official on Latin America and the State Department's top hostage negotiator.

Easing US oil sanctions

The release came hours after Venezuelan President Nicolas Maduro signalled an interest in improving relations with the US amid Russia's invasion of Ukraine and concerns in the United States over rising gas prices.

The weekend meetings focused not only on the fate of Americans held in Venezuela but on the possibility of easing US oil sanctions on the OPEC member, which is a close Russian ally, to fill the supply gap. President Joe Biden on Tuesday banned Russian oil imports in response to Moscow's invasion of Ukraine.

There was no immediate word on the whereabouts of the released detainees, though they were expected to be flown out of Venezuela to the United States without delay.

The State Department declined to comment on Tuesday evening. 

But Cardenas's release was confirmed by Foro Penal, a non-governmental group, and by a person familiar with the matter who was not authorised to discuss the issue by name and spoke on condition of anonymity.

READ MORE:US delegation holds energy talks with Venezuela's government

Jailed Americans

Washington has sought the release of at least nine men, including those known as the "Citgo 6," two former Green Berets and a former US Marine.

Roger Carstens, the special presidential envoy for hostage affairs, came home empty-handed from a previous trip to Caracas in December. 

But he returned to Venezuela this weekend with other administration officials including Juan Gonzalez, the National Security Council director for the Western Hemisphere, and Ambassador James Story, who heads the US government’s Venezuelan Affairs Unit out of neighboring Colombia.

Cardenas and five other executives of Houston-based Citgo, a subsidiary of Venezuela’s state-owned oil giant, had been in detention in Venezuela since 2017 over a never-executed plan to refinance billions in the oil company’s bonds. The US government has pressed for their release.

Three other Americans are also being held in Venezuela — two former Green Berets, Mark Denman and Airan Berry, who were arrested for their involvement in a confusing plot to overthrow Maduro, and former US Marine Matthew Heath, detained on weapons charges.

READ MORE:US, Venezuela make 'scant progress' in talks over easing oil sanctions