Venezuela's President Nicolas Maduro speaks during his visit to a vehicle production plant in Las Tejerias, Venezuela March 21, 2019. Miraflores Palace/Handout via REUTERS

WASHINGTON (Reuters) - The Trump administration on Friday warned the government of Venezuelan President Nicolas Maduro over the detention of Americans, including six executives from Houston-based oil company Citgo Petroleum who have been jailed since 2017.

“We will hold Maduro and his prison officials to account for their safety and well-being,” the U.S. State Department said in a statement, adding that the Citgo employees include five individuals with dual U.S. citizenship and one U.S. legal permanent resident.

The United States is concerned about reports of prison officials preventing attorneys and families of detained U.S. citizens from delivering food and denying communication, the statement said.

The State Department statement came a day after U.S. Republican Senators Ted Cruz and John Cornyn called on Maduro to release the six Citgo executives.

The former top employees of Venezuelan PDVSA’s refining subsidiary were arrested in late 2017 and accused of embezzlement and money laundering linked to talks to refinance Citgo’s debt.

The Venezuelan government is battling over Citgo with a group led by opposition leader Juan Guaido, which has appointed its own board to run Citgo.

Guaido invoked the constitution to assume the interim presidency in January, saying Maduro’s re-election was not legitimate.

Most Western countries have backed Guaido, while Maduro has denounced him as a U.S. puppet who is seeking to foment a coup.