The team investigating illegal market practices including insider training has more than doubled in size, the Financial Services Authority (FSA) said today.

There are now 30 people working in its criminal prosecutor team, a rise from 12 less than a year ago, the FSA said today.

The FSA's first criminal prosecution for insider dealing was launched earlier this year.

Sally Dewar, Managing Director of Wholesale and Institutional Markets at the FSA, told the Financial Times: "There is a strong pipeline coming in both civil and criminal cases. We've taken a conscious decision to focus more on criminal cases.

"As the cases develop, we've been pushing ourselves as to whether we can take more of these cases as criminal cases.

"What the market needs to recognise is the burden of proof is extremely high. Some we are going to lose, some of them we are going to win - and we will have to take the rough with the smooth."

In the FSA newsletter Market Watch last month, Ms Dewar said: "Clean markets are vital to the continuing success of London as an international financial centre.

"Market misconduct, particularly in the form of insider dealing and market manipulation is, put simply, cheating and reduces investor confidence in the UK markets.

"Our aim is to have a regime which achieves 'credible deterrence' and ensures a level of market quality we can all be proud of."

A National Audit Office study last year discovered that less than 10% of FSA resources were directed to tackling financial crime and market abuse.

The Treasury-commissioned report also found that less than half of the FSA's supervisory staff felt confident in dealing with financial crime.

As well as increasing numbers in its financial crime team, the FSA has also beefed up its enforcement division.