CARACAS (Reuters) - Venezuelan police seized executives of U.S. refiner Citgo who were under house arrest, their families and an attorney said, hours after U.S. President Donald Trump met with opposition leader Juan Guaido.

Six top Citgo officials were arrested in November 2017 after being called into a meeting at the Caracas office of state oil company PDVSA, which owns Citgo. They were accused of crimes including embezzlement, money laundering and conspiracy.

Washington has called for the release of the group, which includes naturalized U.S. citizens. A Venezuelan court in June ruled that they should stand trial, and in December they were granted house arrest.

Carlos Anez, stepson of one of the executives, said officers said on Wednesday night they were being taken to the Sebin intelligence service for medical exams. They have had no communication with them since.

“Police came to the apartment, told my father that they had to take him, to bring a change of clothes, they took his GPS off his ankle and took him away,” said Anez.

Alirio Zambrano, a brother of two of the jailed executives, wrote on Twitter, “My brothers Alirio Jose and Jose Luis were taken abruptly from their house arrest last night; we demand to know their whereabouts but more importantly their freedom!”

“At this time we know that they are in the Helicoide (Sebin headquarters), all together in the same cell, even though the house arrest has not been revoked by the court,” said Jesus Loreto, a lawyer representing Tomeu Vadell.

“CITGO believes that the detention of these men as political prisoners violates their fundamental human rights,” the company said in a statement to Reuters. “We continue to support the detainees’ families, including by providing them with resources for legal expenses, health care coverage, and more.”

Venezuela’s information ministry did not immediately reply to a request for comment.

The group includes former Citgo vice presidents Jose Luis Zambrano, Alirio Jose Zambrano, Jorge Toledo, Tomeu Vadell and Gustavo Cardenas, and former President Jose Pereira.

In 2019 the men’s family members and lawyers wrote to the U.S. government asking the State Department and lawmakers to help win their release. U.S. Vice President Mike Pence met with the family members last April.

Venezuela opposition leader Juan Guaido took control of Houston-based Citgo, the government’s most profitable overseas asset, earlier this year after Washington recognized him as the country’s legitimate president.

President Nicolas Maduro retains control of most state functions and the Venezuelan operations of PDVSA, which are under U.S-imposed sanctions.