MADRID - Spain's Supreme Court acquitted today a man accused of conspiring to help commit the Sept 11 attacks on New York and Washington, court papers said.

Judicial sources said the man, known as Abu Dahdah, would serve 12 years in jail for leading a terrorist group rather than the full 27 years to which he had been sentenced.

Abu Dahdah, whose full name is Imad Eddin Barakat Yarkas, was accused of being an al Qaeda member.

"We must absolve, and we do absolve, Imad Eddin Barakat Yarkas of the crime of conspiracy to commit terrorist murder for which he was accused," the court document said.

It added that other convictions of Abu Dahdah still stood.