Hamburg  - A German second-division club is at the centre of a controversy over Ramadan after sending a written warning to three players for observing the Islamic holy fasting month.

FSV Frankfurt told Mail's Soumaila Coulibaly, Gambian Pa Saikou Kujabi and Moroccan Oualid Mokhtari their decision to fast had considerably affected their performance and was "a serious violation of their employment contract," Bild newspaper reported Tuesday.

The club had included a clause in the contracts forbidding players to fast without express permission.

"Ramadan clause! Professionals warned because they fasted," said the Bild headline over a report which said the three players had now referred the matter to their lawyers.

"This clause in the contract is in my view against the law," lawyer Frank Rybak of the German professional footballers' association VDV told German Press Agency dpa.

The Bundesliga has many Moslem players who observe Ramadan, which this year ran from August 22 to September 19, by not not eating and drinking between dawn and dusk.

A German Football League specimen contract calls on Bundesliga players to adopt a professional lifestyle but makes no mention of fasting or dieting.

The club said in a statement its warning to the players was not related directly to "the fact of fasting" and was "in no way an attack on religious freedom" but was for failing to adhere to a contractual agreement and a further verbal instruction.

The club said it had included the clause to make it clear that all types of fasting or dieting, both of which could affect performance, had to be cleared with the management first.

Rybak said that although many players in German football observed Ramadan, they sought to balance their religious beliefs with day-to-day training and playing.

"I know of no player who goes without food during the day for four weeks," he said.

Bayern Munich's France midfielder Franck Ribery, Stuttgart's German international Serdar Tasci and Hoffenheim striker Demba Ba have all said recently they observed Ramadan by fasting during days when there were no games but not on match days.(dpa)