WRAPUP 3-Gunships and planes strike Pakistan Taliban in Swat

* Military says 55 militants killed on Saturday in Swat

* Hundreds of thousands displaced

* U.S. drone attack kills at least five

* 18 militants, one soldier killed near Afghan border

By Junaid Khan

MINGORA, Pakistan, May 9 (Reuters) - Pakistani helicopter gunships and warplanes hit Taliban positions in the militants' Swat Valley stronghold on Saturday, while a curfew prevented civilians from fleeing the fighting.

The struggle in the northwestern valley 130 km (80 miles) from Islamabad has become a test of Pakistan's resolve to fight a growing insurgency that has alarmed the West.

The military said up to 55 militants were killed in the day's clashes in Swat and four soldiers wounded, and that several militants had died in separate clashes close to the Afghan border. The figures could not be independently confirmed.

Pakistan's army went on a full-scale offensive after the government ordered troops to flush out militants from the Islamist stronghold, once an exotic tourist destination.