Vietnam President Nguyen Xuan Phuc has resigned, state media said Tuesday, after days of rumours he was about to be sacked as part of a major anti-corruption drive that has seen several ministers fired.

Phuc has "submitted his resignation from his assigned positions, quit his job, and retired", state news agency VNA said.

Phuc's sudden departure is a highly unusual move in communist Vietnam, where political changes are normally carefully orchestrated, with an emphasis on cautious stability.

State media said the communist party had ruled he was responsible for wrongdoing by senior ministers under him during his 2016-2021 stint as prime minister, before he became president.

Two deputy prime ministers were sacked this month in an anti-corruption purge that has led to the arrest of dozens of officials, with many of the graft allegations relating to deals done as part of Vietnam's Covid pandemic response.

Phuc "took political responsibility as leader when several officials, including two deputy prime ministers and three ministers committed violations and shortcomings, causing very serious consequences", VNA said, quoting the party central committee's official statement.

Earlier this month, the country's rubber stamp National Assembly removed Pham Binh Minh and Vu Duc Dam from their positions as deputy prime ministers.

Minh was a minister of foreign affairs while Dam was in charge of the country's handling of the Covid-19 pandemic.

At least 100 officials and businesspeople, including Dam's assistant, have been arrested in connection with a scandal involving the distribution of Covid-19 testing kits.

Thirty-seven people -- many of them senior diplomats and police -- have also been arrested in an investigation over the repatriation of Vietnamese during the pandemic.

- Corruption, infighting -

After closing its borders to slow the spread of the coronavirus, Vietnam organised nearly 800 charter flights to bring citizens home from 60 countries and territories.

But travellers faced complicated procedures while paying exorbitant airfares and quarantine fees to get back to Vietnam.

Phuc, 68, was elevated to the largely ceremonial role of president in April 2021 after winning plaudits for the country's broadly successful handling of the pandemic.

Authoritarian Vietnam is run by the Communist Party and officially led by the party general secretary, president, and prime minister, with key decisions made by the politburo, which now numbers 16.

Le Hong Hiep, a fellow at the ISEAS-Yusof Ishak Institute in Singapore, said Phuc's resignation may also be linked to political infighting.

"It's mainly related to corruption investigations but we cannot rule out the possibility that his political rivals also wanted to remove him from his position for political reasons," he told AFP.

Communist Party leader Nguyen Phu Trong, the architect of what is Vietnam's largest-ever anti-corruption drive, is due to step down in 2026.

"Some politicians will try to get the (top) prize and because of the competition from their rivals -- in this case Mr Phuc is one of them -- they may want to remove him to clear the way for the other candidate to get the top job."