One of the commanders killed was to believed have been among five Taliban freed from Afghan jails last month in exchange for an Italian hostage, the US-led coalition said, citing intelligence reports.

"Two other senior Taliban commanders, believed to have been killed in the battles, were known enemies of the Afghan government for the past three years," it said.

A senior Afghan defence ministry official agreed with the statement about the April 27 and 29 fighting in the western province of Herat.

"A big number of senior Taliban commanders were among those killed," he said on condition of anonymity. "A Taliban commander swapped for the Italian journalist was also killed."

The late-March swap was widely condemned with critics saying it could result in copy-cat kidnappings. Less than a week later an Afghan medical team was snatched; two French aid workers and three Afghans were captured April 3.

In both cases, the Taliban said it wanted some of its prisoners to be freed in exchange for the hostages. It has also demanded the withdrawal of French troops in Afghanistan for the release of the French group.

The militants released one of the French hostages a week ago; on Saturday it said it would decide on the fate of the Frenchman and his colleagues after France's May 6 presidential election.

The Herat battles involved US Special Forces, other coalition soldiers and Afghan troops.

The coalition said it killed 136 Taliban -- one of the biggest tolls in months -- but a series of investigations prompted by local claims has found that around 50 civilians, including women and children, were among the dead.

Under pressure after a string of incidents involving civilian casualties, the coalition is investigating the claims while pointing out that the Taliban are known to use civilians as human shields.