PESHAWAR, Pakistan — A purported Taliban commander has claimed responsibility for a market bombing in northwestern Pakistan that killed an anti-Taliban mayor and 11 others.

The man, who gave only one name, Omar, said in a telephone call from an undisclosed location that the group’s local fighters carried out the Sunday attack.

The man, whose identify could not be confirmed, said the mayor was targeted in the attack near Peshawar because he had set up a militia and was helping fight the militants.

The Taliban have carried out a series of attacks aimed at pressuring the government to abandon an offensive launched in mid-October in South Waziristan, the main Taliban and al-Qaida sanctuary in the country.