MINGORA, Pakistan (Reuters) - Pakistani forces killed 23 militants early on Tuesday in fighting that erupted after insurgents fired on troops during a search operation in the country's northwest, police and intelligence officials said.

The search was launched after a suicide bomb attack on a paramilitary fort in Lower Dir district, where troops killed hundreds of militants in an offensive last year.

"The fighting began when miscreants opened fire on troops searching the area after reports of militant movement there," Dir's top police chief, Mumtaz Zireen, told Reuters.

Zireen said 23 militants were killed in the pre-dawn exchange of fire in the Maidan area.

Independent verification was not immediately available. Militants often reject and dispute casualty figures issued by officials.

Fresh violence after a relative lull has again focused attention on Pakistan's performance against homegrown Taliban insurgents.

At least 42 people were killed and 175 wounded when two suicide bombers struck Pakistan's most important Sufi shrine last week, the second major attack in a month on Pakistan's cultural hub and traditional seat of power, Punjab Province.

(Reporting by Junaid Khan; Writing by Augustine Anthony; Editing by Michael Georgy and Ron Popeski)