MOSCOW (AP) — Russian opposition leader Alexei Navalny says that he has undergone eye surgery in Spain after being attacked last month.

Navalny suffered a severe chemical burn in his right eye last month when an attacker doused him with green antiseptic a week ago. Navalny's supporters identified the attacker as a pro-government activist, but police haven't made any arrests.

Navalny wrote on Instagram on Tuesday that he had been operated on Monday at a Barcelona clinic and that doctors expect the vision in his right eye to be restored in several months.

After being denied travel documents for five years, Navalny, who is serving a five-year suspended sentence in a dubious embezzlement case, was issued a passport to travel last year.