Gwent police have now charged 10 councillors from Blaenau Gwent County Council with criminal offences relating to false accounting. They include mayor Steve Barnett, ex-leader Bernard Assinder and former mayor Colin Jones.
In all, 25 councillors on the 42-strong council have been interviewed by the police, whose inquiry has focused on expenses fiddles involving more than pounds 100,000. It is claimed that some people allegedly filed expenses claims for attending conferences in other counties, while also claiming for simultaneous council meetings.
Politically, the court cases could damage the Labour Party, which has been troubled by allegations of malpractice in other parts of the "Old Labour" industrial heartland. South Wales has now been added to a list that includes councils in Scotland, Hull and Doncaster. Blaenau Gwent includes the old constituency - then known as Ebbw Vale - of two of Labour's greatest left-wingers, Aneurin Bevan and Michael Foot.
The current MP, Llew Smith, is a traditional socialist and former labourer, who opposed devolution because, he says, he despises nationalism. In the old coal mining and steel area, where, locals joke, they weigh the Labour vote rather than count it, his 28,000 parliamentary majority is the second- largest in Britain. He admitted that Welsh Labour was "in chaos".
But Janet Davies, the Plaid Cymru local government spokeswoman, said being a councillor guaranteed an expense allowance and perks, and that it could lead to better housing and other favours. "I think some of the people who have been arrested in Blaenau Gwent didn't even realise they were doing anything wrong."
Plaid Cymru is the main opposition party in Wales, with four MPs against Labour's 34. The Liberal Democrats have two MPs, and the parliamentary Conservatives in Wales became extinct at the 1997 general election. According to Ms Davies, Labour's 70-year-old domination of Welsh politics has meant that corruption and self-serving leaders have been commonplace. "The people have always known that their local councillors are corrupt but the hatred of the Tories is intense. They continue to support Labour but a lot of the local councils are very badly run."
The local Labour organisations were intolerant of opposition, she added, and not above using "rough house" tactics and physical intimidation.
The arrests in Blaenau Gwent have only added to the problems for Labour Party managers in London and Cardiff. Welsh Labour - still reeling from the resignation of Ron Davies, the Secretary of State for Wales - is now embroiled in rows over leadership of the Welsh National Assembly.
Leading political figures in the valleys are also angered by what they see as attempts to block working-class or left-wing candidates from standing for the National Assembly. A legal action against the party's nomination procedures has also been started.
The strong possibility of protracted court appearances involving Blaenau Gwent councillors as Labour gears up for the National Assembly, and the local and European election campaigns in May, has only added to the party's woes.