Australian captain Michael Clarke has apologised to India for breaching cricket’s etiquette.

Clarke’s apology came after India launched an obstruction appeal against the Australian batsman on Tuesday’s opening day of the fourth Test in Adelaide.

The controversy, in the over before tea, came when Clarke nudged a single from Virat Kohli’s spin bowling.

Indian fielder Ravi Ashwin pounced from square leg and threw at the stumps at the bowler’s as Clarke extended his bat to make his ground.

The ball ricocheted from Clarke’s bat into the outfield – and the Australian skipper broke the unwritten gentleman’s agreement of not running again.

Clarke took a further two runs as India appealed that he blocked the throw, but replays showed the Australian did not change course during the initial single.

Ashwin said Clarke, who made an unbeaten 140 as Australia amassed 3-335, apologised for taking the extra runs after the thrown ball deviated from his bat.

“We were not really sure if he had run into the line of the throw or not … so we just wanted to check on that and had a polite inquiry,” Ashwin said.

“He (Clarke) went to the umpires and said if he could take back those two runs – and he did it really instinctively.

“Anybody can mistakes.

“He was quite pardonable because he immediately went and said ‘I’m sorry, I shouldn’t have done it’, it is commendable on his part.”