Police in Indian-administered Kashmir say they have arrested a man in connection with Wednesday's gun and grenade attack in Srinagar in which five security personnel were killed.
Media reports, quoting police sources, say the man was a resident of Pakistan.
India has said the two gunmen killed in the attack appeared "not local but from across the border" - a reference to Pakistan.
Pakistan has rejected the accusation, calling it "counter-productive".
Reports quoting police sources said that diaries, an Indian Sim card, a tube of ointment made in Pakistan and papers had been seized from the man, reportedly from Multan in Pakistan.
India's Home Minister Sushil Kumar Shinde said in parliament on Thursday that the two militants killed in Wednesday's attack appeared to be of Pakistani origin, and the diaries recovered from them contained Pakistani phone numbers.
Pakistan has said it "condemns such actions of terrorism in the strongest possible terms and calls upon the government of India to carry out a thorough investigation... before levelling such accusations which are counter-productive and serve no purpose".
The Hizb-ul Mujahideen militant group said it had carried out the attack and threatened more violence, according to local media reports.
A curfew was imposed in Srinagar following a day of violence on Wednesday in which at least eight people were killed.
Militants killed five security personnel the gun and grenade attack in the city.
The curfew was imposed after another man was killed later in the day in clashes between police and protesters.
Indian-administered Kashmir has seen an insurgency against Indian rule since 1989, but violence has declined in recent years.