Police in the Basque region of Spain say they have broken up an important unit of the Basque separatist organisation, ETA, in an overnight raid in the town of Guernica.

The police say a woman member of ETA was killed in an exchange of gunfire during the operation.

Thirteen people were arrested, and a number of documents and wepons seized during the raid, which follows a series of operations against Basque separatists.