LIMA - Peru's vice-president has resigned from her post after declining the opposition's nomination to be interim leader, saying she hoped it would pave the way for a new general election.

Mercedes Aráoz said the "constitutional order had broken" and that the country faced a "grave institutional crisis".

President Martín Vizcarra on Monday dissolved Congress, but opposition MPs suspended him and swore in Ms Aráoz.

On Tuesday, armed police blocked legislators from entering Congress.

Some 20 MPs were inside the congressional building in the capital, Lima, refusing to leave in protest against President Vizcarra's dissolution, while streets around parliament were in lockdown.

In a late-night post on Twitter, Ms Aráoz cited a statement by the Organization of American States that Peru's constitutional court should determine the legality of Mr Vizcarra's decision to dissolve Congress.

She said she hoped that her resignation would lead to a general elections being called as soon as possible, for "the good of the country".

Mr Vizcarra dissolved Congress, saying opposition legislators had blocked him from passing a raft of anti-corruption measures. He argued that his move was constitutional, but opposition parliamentarians said it was dictatorial and have refused to leave the building.

A majority of the opposition-controlled Congress then voted in favour of suspending Mr Vizcarra for a year, and declared Ms Aráoz acting president. But the government claimed the moves were null and void because they had occurred after Congress had been dissolved.(FA)