Marin Cilic pulls out of Montreal Masters after claims of failed drug test

Croat does about-turn on playing to increase speculation that he will soon be banned

Marin Cilic has pulled out of next week's Montreal Masters, his second withdrawal from a tournament since unconfirmed reports emerged claiming that the world No 15 had failed a drugs test. Cilic had been announced as one of the seeds for Montreal, where most of the world's leading men will be competing, but the tournament have announced that the 24-year-old Croatian would not be taking part.

Cilic has not played anywhere since Wimbledon, where he withdrew before his second-round match against Kenny de Schepper. Local media claimed last month that Cilic had been informed at Wimbledon that he had failed a drugs test at the Munich Open in April. It was reported that his 'incautious use of glucose' had resulted in the positive test, though glucose is not a banned substance.

Cilic's management company failed to respond to a request for information about when he might return, while the International Tennis Federation, which administers the drug-testing programme, refused to comment on whether or not the 2012 Queen's Club champion had failed a drugs test. The ITF follows a strict policy of releasing information on such matters only if tribunals find players guilty of offences.

In serious cases the ITF can impose a provisional (but not publicised) suspension after a failed drugs test, but it is often up to the player to decide whether or not he or she wants to compete pending a tribunal. If Cilic has failed a test he might have decided not to play in the interim.

It usually takes about three months for a player to come before a tribunal following a positive test, which could mean a Cilic hearing is imminent. There had been speculation in Croatia that he might be handed a three-month retrospective ban, which could have explained why he would have returned in Montreal. Ranking points and prize money earned during retrospective bans are withdrawn and a three-month suspension might have ended before the start of the Montreal tournament.

Anything longer than a three-month ban would have serious consequences for next month's Davis Cup World Group play-off between Croatia and Britain in Umag. Cilic is Croatia's best player and would represent the country's main hopes of beating Britain, especially if Andy Murray lives up to his commitment to play for Leon Smith's team. However, he cited a knee injury for pulling out of Wimbledon and last month's clay-court tournament in Umag in his native Croatia and has never admitted to failing a drug test.

Meanwhile the ITF is still waiting to hear whether Serbia's Viktor Troicki has appealed against the 18-month suspension imposed last month for failing to provide a blood sample at a tournament earlier this year. Troicki, who insisted that a doping control officer had told him he could miss a drugs test after he complained of feeling unwell, said after his hearing he would take his case to the Court of Arbitration for Sport.

Following criticism that drug-testing procedures in tennis are not strict enough, the ITF is in the process of establishing a system of "biological passports". It is expected to be in place by the end of the year.