Arsenal manager Arsene Wenger has admitted he cannot be sure when midfielder Jack Wilshere will make his comeback from injury. The 20-year-old English international has been out of action since July last year with an ankle injury suffered during a friendly against Major League Soccer (MLS) club New York Red Bulls.

He was believed fit in January and made a brief comeback which only seemed to aggravate the injury. He has been missing ever since. Wenger has indicated that the youngster is making a rapid recovery but clearly the experience of sending him back into the thick of the action prematurely has taught the Frenchman to be more cautious about the highly rated player.

"It is impossible to set a concrete deadline at the moment, but it is all okay. He is as quick as we expected him to be. His ankle is good and his knee is good. There is no setback. It difficult to say, 'It will be this week in September or October' when he is back in training. He has been out for a year and I don't want to put any pressure on him," ESPN quoted Wenger as saying.

Apart from Wilshere, Ghana midfielder Emmanuel Frimpong and Czech international Tomas Rosicky will also miss the start of the season. Frimpong picked up a knee injury during his loan spell with Wolves last season and Rosicky sustained an injury when playing for his national team at the 2012 European Championships. Wenger has indicated Rosicky's injury (plantaris tendon) will take six to eight weeks to heal.

Worse still, Arsenal's well documented injury list will also include French defender Bacary Sagna, who suffered a broken leg during Arsenal's clash with Norwich City towards the end of last season. He is not expected back before August.

However, on a more positive note, Wenger has confirmed Spanish midfielder Mikel Arteta, French midfielder Abou Diaby and goalkeeper Lukasz Fabianski, who were all injured last season, are now available for selection.

Finally, Wenger has confirmed wantaway striker Robin van Persie will not be part of the 24 man squad set for a pre-season tour of Asia. He also added he had decided to leave several players behind because of fitness issues.

"Some of them [will not go on tour] because they are too far behind to be competitive, but most of them will go, the German players [Podolski and Mertesacker] are just back in training on Saturday so they will be late. Some players have to work on their fitness so are a bit behind, like van Persie, like Koscielny, like Giroud, who came in later. They are not ready to play games," said Wenger, according to Arsenal's official website.

Arsenal will play Premier League champions Manchester City in a pre-season friendly in Beijing's Olympic "Bird's Nest" stadium on 27 July.