By John May and David Walmsley BBC Sport exclusive

Football's drug tests have been branded a shambles because of an alarming loophole in the way they are conducted.

BBC Sport has been told by a sampling official that the Football Association's drug checks can be bypassed despite surprise visits to club training grounds.

And the news will be deeply concerning given the revelations in the BBC Real Story investigation into drug use in football.

"There is always a way round things. Our visits to clubs are supposed to be an out-of-the-blue surprise, but it's far from a secure system," said one of UK Sport's Independent Sampling Officers (ISO).

UK Sport carries out testing on behalf of the FA, which issues instructions as to when and where they are carried out.

TESTS IN THE SPOTLIGHT Testing introduced in 1994 1,200 tests carried out a year at pro and amateur levels Majority conducted at training grounds One nandrolone case under investigation Most positives for recreational drugs

"The FA dictates where and when tests are carried out. We only do their bidding," said the official.

"I get a list from UK Sport long in advance and I would not be surprised if others know about it.

"When we get to a club, we can only randomly test the players who are there and in training on that day.

"If a club knows in advance we're coming, and the club suspects one of their players, they keep him off training and his name doesn't appear on the list I am given.

"I visited one Premiership club recently and the player selected told me it was the first time he had been tested in 12 years of his career.

"The whole thing is a horrible mess."

The FA has come under fire following allegations that Chelsea goalkeeper Mark Bosnich tested positive for cocaine.

One Premiership player told me it was the first time he had been tested in 12 years of his career UK Sport drug tester

Circumstances surrounding the leaking of Bosnich's test have led to accusations that the FA's drug-testing programme is flawed.

Arsenal manager Arsene Wenger has led the call for tougher and more regular testing - with an emphasis on post-match checks.

An FA spokesman admitted that random testing patterns are drawn up months ahead of training ground visits.

Despite the possibility of the testing schedule being leaked, the spokesman insisted that "the scope for avoidance is not that substantial".

He said: "It is planned at the beginning of the season exactly when the testers are going to turn up at club A, club B etc. But there is no advance warning of that."

And he also rejected Wenger's suggestions that testing is not taken as seriously as other European countries.

"We are second only to Italy in the number of tests we carry out," he said.

"We do probably around twice as many tests as they do in Germany, France or Spain.

"We test at more levels than any other country and we put the onus far more on out-of-competition testing.

"We feel that turning up randomly and unannounced at training grounds is the best way of catching people who are taking banned substances. Other countries are beginning to follow suit."

The FA's comments were backed by UK Sport, who pledged to investigate any breaches of security.

We would thoroughly investigate any allegations of behaviour that threatened the integrity of the testing programme UK Sport spokesman

A spokesman said: "The FA operates by far the largest testing programme of all sports in the country.

"Footballers in England can be tested on any day during the week, as well as after matches.

"All the tests are carried out with no advance warning - a significant deterrent to any player who may be tempted to use drugs.

"No other country carries out tests on footballers seven days a week.

"Our ISOs are made aware in advance of where and when they will be testing to ensure that they are available to carry out the tests. This is normal procedure for all sports.

"UK Sport would thoroughly investigate any allegations of behaviour that threatened the integrity of the testing programme, such as the sharing of such information with the clubs.

"However, all our ISOs are highly trained professionals who work to strict international guidelines, and no such investigations have ever been necessary."