The United States has issued a new warning to Venezuela after imposing sanctions on President Nicolás Maduro, saying it holds him “personally responsible” for the health and safety of two opposition leaders jailed on Tuesday.

In a statement released by the White House late on Tuesday, US President Donald Trump condemned “the actions of the Maduro dictatorship” and said Leopoldo Lopez and Antonio Ledezma were political prisoners held illegally by the Venezuelan government.

“The United States holds Maduro – who publicly announced just hours earlier that he would move against his political opposition – personally responsible for the health and safety of Mr. Lopez, Mr. Ledezma, and any others seized,” Trump said.

Earlier, Secretary of State Rex Tillerson called the arrests “very alarming”.

The UN High Commissioner for Human Rights (OHCR) also weighed in from Geneva.

“There are many reports that excessive force has been used in the context of demonstrations,” said OHCR spokeswoman Ravina Shamdasani.

“We also have reports that they (security officials) have conducted house to house raids, and taken people and detained them. We are calling on the government to refrain from taking any further steps, to make an already bad situation even worse.”