Venezuela's contested new assembly fired the country's dissident attorney general, Luisa Ortega, on Saturday, and ordered she stand trial, in a move certain to provoke greater international criticism.

The body, which made the sacking its first order of business, also said it planned to operate as Venezuela's supreme power for up to two years.

Troops surrounded the office of Ms Ortega on Saturday ahead of the move, as the newly installed constituent assembly began the session aimed at removing her from power.

Ms Ortega was suspended by the supreme court on Friday evening, hours after the assembly - derided by government critics as an illegitimate power grab - convened for the first time.

On Saturday morning she tweeted a photo of the soldiers outside her office, saying: "I reject this siege by the public ministry. I denounce before the national and international community this arbitrariness."