By Saud Mehsud and Faris Ali

HANGU, Pakistan (Reuters) - A suicide bomber killed 19 people and wounded 45 on Friday in a crowded market outside two mosques from separate Muslim sects in Pakistan's restive northwestern town of Hangu, police and officials said.

The attack occurred in a tight lane that houses both a Shi'ite and a Sunni Muslim mosque. Some officials said the anti-Taliban Sunni Supreme Council often holds its meetings in the Sunni mosque, which was the possible target.

But district police chief Muhammad Saeed said the attack was aimed at Shi'ites and Sunni Muslims were also victims.

"Most of the dead were moving in and out of the mosques in the marketplace after Friday prayers when the bomb went off," senior police officer Imtiaz Shah said.

Hangu, part of Pakistan's border region with Afghanistan, has been racked by sectarian violence between Sunni and Shi'ite tribes whose mosques, homes and shops are often close to one another.

Hangu is just a few km from Parachinar, which has a significant Shi'ite population against whom hardline Sunni militant groups have launched attacks for years.

No group had claimed responsibility for the attack by early evening.

(Writing by Mehreen Zahra-Malik; Editing by Nick Macfie and Ron Popeski)