International Desk: The US holds Venezuelan President Nicolás Maduro "personally responsible" for the safety of two seized opposition leaders, President Donald Trump has warned.
In a statement, Mr Trump also called for the immediate and unconditional release of all political prisoners.
Leopoldo López and Antonio Ledezma, who had been under house arrest, were taken to a military prison on Tuesday.
This came after Sunday's controversial vote for a constitutional assembly.
At least 10 people were killed, as the opposition boycotted the election.
President Maduro said the poll was a "vote for the revolution", arguing that the move would create peace and foster dialogue by bringing together different sectors of Venezuela's polarised society.
The opposition said late on Tuesday that it had decided to hold a demonstration against the new assembly on Thursday.
Opposition lawmaker Freddy Guevara tweeted (in Spanish) the rally would be held on "the day the dictatorship plans to install the fraudulent assembly".
It had originally been thought that the government would open the constituent assembly on Wednesday, thereby evicting the opposition-controlled National Assembly.
risingbd/Dhaka/Aug 2, 2017/Nasim