From Soviet-style letters of denunciation to outlandish rumours of a coup, Hanoi is abuzz with political gossip ahead of a key leadership change this week that has plunged the ruling communist elite into turmoil.

Politics in authoritarian Vietnam rarely attracts public attention. The communists have run the unified country as a one-party state since decades of war ended in 1975.

But in the internet age, bitter factional infighting has transformed the customarily staid Communist Party Congress, which opens on Thursday in Hanoi, into political theatre.

Leaks and counter-leaks of internal memos, letters of denunciation and detailed responses are circulating online. State media has urged people not to read such "poison," but many have made up their own minds.

"I don't trust the system. It's all bureaucracy, corruption, fights for power," party member and high-ranking state employee, Nguyen Minh, 45, told AFP.

Minh, who AFP has not fully identified, said she had grown wealthy from her position but now felt trapped. She said she was tired of enduring endless discussion of the congress at work.

She admits she's sent her daughter overseas for education -- and would accept her choosing not to return.

"Capitalism is better than socialism... Here we are living in a cage, it's difficult to inhale fresh air," she said.

At the week-long meeting starting Thursday, the country's top three jobs -- Party General Secretary, President, Prime Minister -- are up for grabs, with all incumbents technically due to retire.

Normally, a deal is agreed months in advance. Analysts say the delay this year highlights a struggle between the party's traditional old guard and a more modern breed of politician, embodied by Prime Minister Nguyen Tan Dung.

- 'Who the hell knows' -

Dung, a pro-western reformer who presided over Vietnam joining the WTO and the US-led Trans Pacific Partnership trade deal, and has been outspoken over Vietnam's maritime dispute with China, was tipped by analysts to move up to the powerful party leader position.

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But the incumbent, Nguyen Phu Trong, seen as more a conservative apparatchik and closer to Beijing, has been manoeuvering to stay on and install allies in top posts.

A political survivor, Dung has weathered corruption allegations, attempts to unseat him, and the failure of the state-owned enterprise system that he championed after becoming premier in 2006.

With a powerful network of allies, he could yet emerge as party secretary, said Jonathan London, a Vietnam expert at City University of Hong Kong.

"Certainly his candidacy appears to be on the ropes but who the hell knows? He could yet mount a comeback... unlike China, the party congress in Vietnam is not entirely scripted," he said.

Neither side will dramatically change course on key issues such as the dispute with Beijing over the South China Sea as Vietnam is a large country ruled "by committee," London said.

But a Hanoi-based diplomat warned a win for Trong's faction could skewer badly needed economic reforms by bumping competent and less dogmatic politicians to the sidelines.

With a youthful population of some 90 million in need of jobs -- and an economy growing at some seven percent a year -- this could be the difference between cashing in on tremendous potential or "muddling through" for another five years, they said.

- 'It's a joke' -

While the party is busy arguing over changes at the top, dissident Le Cong Dinh said that as far as the country's youth is concerned they might as well be rearranging deckchairs on the Titanic.

"Only intellectuals care about these matters. The majority do not," said Dinh, a lawyer who is currently under house arrest.

Most young people "want more radical political change so they can have better lives", said army general and lifelong party member Nguyen Trong Vinh.

This is highly unlikely for now as the party will unite in a bid "to preserve the Communist 'house' despite factional struggles," he added.

For many, fed up with pervasive corruption, economic mismanagement, and draconian persecution of regime critics, the party congress is a waste of time and money.

"It's a joke. Whoever becomes party leader, prime minister, president -- it's no change for the country, they're all the same," said war veteran Tran Tu Luc, who has been following the process closely.

The 72-year-old has been a party member for forty years but said he has lost faith in the communist system, which he felt was "destroying" his country.

"I'm so disappointed," he said, adding he stopped going to party meetings in his neighbourhood as he was fed up with "clichés and bullshit arguments."