Bingley sports turf specialists behind Wembley Stadium’s problematic pitch have quit, it has been revealed.

The announcement by the Sports Turf Research Institute (STRI), at the St Ives Estate, follows mounting criticism of the playing surface that reached a crescendo after the FA Cup semi-finals.

STRI, which has acted as pitch consultants for 13 months, will leave at the end of this month.

A spokesman for STRI stressed that the split had been “amicable”.

Its chief executive Gordon McKillop, said: “We have had many constructive and positive discussions with Wembley over the last few weeks on what would be the best way forward to make significant improvements to the pitch.

“In relation to this STRI presented an alternative strategy for 2010 to change the construction of the pitch, which Wembley agreed was the best way forward and is now proceeding with this.

“We are pleased that Wembley has adopted our proposed strategy which should see improvements to the pitch during 2010.

“This new structure of pitch does not require the previous level of research and consultancy from the STRI team and, therefore, we feel it is the right time to resign.”

After the FA Cup semi-finals Tottenham manager Harry Redknapp described the surface as “ridiculous” and Spurs and England striker Peter Crouch said it was the worst Wembley pitch he had ever seen.

Wembley re-laid the pitch at a cost of £125,000 and embarked on a major review of the surface. It is anticipated, however, that unless there is major reconstruction of the pitch it may have to be relaid several times a year.

STRI has worked on more than 10,000 sports facilities in 32 countries, ranging from world-renowned venues to local clubs.

It has been involved with research on sports stadiums, grounds and courses including Wimbledon, Hickstead – the home of British show jumping – and St Andrews, the home of golf.

The company is also involved with ensuring that playing surfaces remain in good condition once the world’s football stars have departed following the World Cup in South Africa.

Its role includes overseeing the preparation of ten showpiece stadium pitches, 32 training camps and 15 training sites across South Africa.

STRI employs 80 people and has a turnover of £3.5 million.