Image copyright AFP/Getty Images Image caption Dinh La Thang is a former chairman of PetroVietnam

A top Vietnamese official has been sacked for "violations" while running national oil and gas firm PetroVietnam, in a rare public censure by the ruling Communist Party.

The government said on Sunday that Dinh La Thang, 57, was no longer part of the top decision-making Politburo.

Mr Thang's alleged misconduct was first leaked on social media last year.

His sacking comes amid a wider crackdown on PetroVietnam, the country's largest enterprise.

It is extremely uncommon for a Politburo member to lose their place in the one-party state. Since Vietnam started economic reforms in 1986, only two other Politburo members have been dismissed.

'Serious violations'

Mr Thang is said to have committed the violations between 2009 and 2011 while he was chairman of PetroVietnam.

Last September, writer Huy Duc attacked Mr Thang on Facebook with articles accusing the politician of being responsible for a recent huge loss at PetroVietnam.

Although Huy Duc's articles, which seemed to be based on leaked documents, polarised public opinion on the internet, the issues he raised were not reported in state media.

In late April, the Central Inspection Committee, the top watchdog of the party, suddenly announced it had investigated and held Mr Thang responsible for "serious" violations at PetroVietnam.

The party's inspectors accused Mr Thang of allowing PetroVietnam to make loans to the local Ocean Bank that caused "serious losses" to the company.

They also said Mr Thang had advised the prime minister "to designate many bidding packages that failed to meet legal regulations".

Image copyright AFP/Getty Images Image caption PetroVietnam is the country's national oil and gas firm, and also its largest enterprise

On Sunday, a government statement said more than 90% of the party's central committee had voted to remove Mr Thang.

It said he had committed "serious violations in his leadership, command and staff works", which "hurt the Party's reputation" and caused "a loss of confidence" among people and party members.

Rising star

Mr Thang, a former transport minister, became a member of the new Politburo at the party congress last year and was made the party's chief of Ho Chi Minh City, the country's largest city and commercial hub formerly known as Saigon.

The party is expected to soon name a new party chief for the city, a position always held by a Politburo member.

He was catapulted into political stardom for being unusually outspoken among normally reticent officials, and was known for his forthright rhetoric on state media.

His fall from grace follows other arrests at PetroVietnam and linked companies.

Another former PetroVietnam chairman was arrested in 2015 and later expelled from the Communist Party. Three other senior executives are also facing possible sanctions.

Last year four senior employees at a construction subsidiary of the firm were prosecuted for mismanagement that allegedly cost the company $150m (£116m).

Communist Party chief Nguyen Phu Trong, who is effectively the most powerful man in Vietnam, is serving his second term. He has launched an anti-corruption campaign and has issued resolutions aimed at improving ethical conduct among party members.

Image copyright Reuters Image caption Mr Trong is effectively the most senior leader in Vietnam

Critics claim that the recent high-profile arrests and trials are mainly the result of political infighting.

However, Mr Trong's supporters say he is seriously concerned about systemic corruption and wants to do more to combat the problem.

Vietnam is ranked 113 out of 176 on Transparency International's corruption index.