Twenty eight AIM companies have had their shares suspended for failing to file their accounts on time.The number of late companies peaked last month prompting advisers to question corporate governance standards on the junior exchange.

The London Stock Exchange took action after 28 companies with December year ends missed the deadline.

PricewaterhouseCoopers’ AIM leader David Snell highlighted the issue on the junior exchange, which has made efforts to tighten its regulations after being criticised about the quality of its companies.

‘Twenty eight companies had their shares suspended in June for not getting their accounts in on time. That tells you something about the corporate oversight,’ said Snell.

The companies covered a wide cross-section of businesses including petrochemical companies, gold producers and tax planners.

A source close to the Stock Exchange said the number of suspensions was higher than usual, putting the situation down to the hostile economic climate.

In its Corporate Governance on AIM study PwC highlighted ‘a wide variation across the whole of AIM. Bigger does not necessarily mean better in terms of governance.’

PwC thought it encouraging that 91% of the top 100 AIM companies published a separate corporate governance report in their annual report, while only 3% chose to fully adopt the Combined Code, seen as the benchmark for listed companies.

‘What we are seeing in general is that there is a relatively limited application of best governance practices,’ PwC said in the report.

There are close to 1,500 companies currently quoted on the exchange.

A London Stock Exchange spokesman said: ‘There is a provision for companies to file their accounts within six months of the year end and you get peaks and troughs [in terms of suspensions.]’

The spokesman added that nine companies had managed to get their bans lifted and have been readmitted to trading.