Batsman Ahmed Shehzad's four-month doping ban has been extended by six weeks because he played club matches during the period of ineligibility, the Pakistan Cricket Board (PCB) said on Friday.

The PCB banned Shehzad for violating anti-doping regulations after he tested positive for a prohibited substance in May and his suspension was scheduled to end on November 10. 

On October 19, the PCB served a notice to the 26-year-old due to him playing during his suspension for the Lahore-based Muslim Gymkhana Cricket Club, which is affiliated with the board.

Shehzad apologised in his response to the PCB but said he was unaware of the rules and did not breach them intentionally.

"First let me unreservedly tender my apology for my error of judgement. Although ignorance of rules is no excuse, I would nevertheless like you to know that I was unaware of the PCB rules," the board quoted Shehzad as saying in a statement.

The PCB had the option of imposing a new ban of four months on the cricketer but decided to extend his original sanction by six weeks due to Shehzad´s "immediate admission of fault", "honesty" and the matches he participated in being "friendly" club games.

The PCB provisionally suspended Shehzad in July after his in-competition urine sample collected during the Pakistan Cup domestic tournament had tested positive.

The PCB did not specify the substance for which Shehzad had tested positive.

Shehzad last played for Pakistan in the two-match Twenty20 series in Scotland in June.

He has played 13 tests and 81 one-day internationals for Pakistan.