BERLIN - Some 24 European countries have been affected by match-fixing and up to 100 games have been manipulated in the past five months alone, said a betting watchdog official on Wednesday.

Speaking as an expert witness at a match-fixing trial in Bochum, Germany, Sportradar CEO Carsten Koerl said match-fixing was on the rise given the financial incentives involved.

"Manipulations are increasing," said Koerl, whose company tracks betting patterns and works with FIFA and UEFA.

"In the past five months we assume that between 70 and 100 games in Europe were manipulated."

He said, however, that given the tens of thousands of games being played each year the number of affected matches represented only a very small percentage.

"There is a clear development in this (betting activity) given that nowadays there are many more possibilities to earn money from this," Koerl said.

He did not say which countries were involved or what leagues were affected.

Four suspects are on trial after a 2009 German police operation unearthed a European match-fixing ring with more than 200 suspected members who fixed or tried to fix around 200 matches across the continent, including three in the Champions League.

European soccer's governing body UEFA at the time had called it the biggest betting scandal in Europe.

Initial estimates had put the illegal gains at about 10 million euros but court officials said the figure was just "the tip of the iceberg."

Further investigations have also implicated German football players from lower leagues.

The trial continues.