Washington, Aug 2 (IANS): US President Donald Trump has said that Venezuelan President Nicolas Maduro is responsible for the the health and safety of two leading opponents of his government who were dragged from their homes by state security agents and sent to prison.

In a statement issued by the White House on late Tuesday, Trump said that opposition leaders Leopoldo Lopez and Antonio Ledezma were "political prisoners" being held illegally by the regime.

"The US condemns the actions of the Maduro dictatorship. Lopez and Ledezma are political prisoners being held illegally by the regime," Trump said in a statement, referring to Maduro's Venezuela for the first time as a "dictatorship".

"The US holds Maduro -- who publicly announced just hours earlier that he would move against his political opposition -- personally responsible for the health and safety of Lopez, Ledezma, and any others seized. We reiterate our call for the immediate and unconditional release of all political prisoners," Fox News quoted the President as saying.

Lopez and Ledezma, who had been placed under house arrest for several weeks, were arrested on Monday night for allegedly plotting "an escape plan", according to the Supreme Court of Justice.

The arrests came after Washington on Monday ordered sanctions against Maduro, describing him as "dictator" for the first time, with the freezing of assets that he may have under US jurisdiction and the ban on financial transactions, Efe news reported.

Washington's decision came in response to Sunday's election of National Constituent Assembly representatives, which it called a "farce".

Despite labelling Maduro a "dictator", the US still considers the Maduro government legitimate and would not recognise a possible parallel executive body formed by the opposition, US Deputy Assistant Secretary for Western Hemisphere Affairs Michael Fitzpatrick said on Tuesday.