An Observer investigation has established that the lone surviving gunman caught by Indian police during last week's terrorist attacks on Mumbai came from a village in the Okara district of the Pakistani Punjab.

Ajmal Amir Kasab, interrogated in custody after last month's attacks, which killed 163 people, reportedly told Indian security officials that he came from a place called Faridkot in the Punjab province. His father was named as Mohammed Amir, married to a woman named Noor. During the past week, Pakistani sources have cast doubt on the authenticity of the leaked information, which has had a predictably explosive impact on relations between the two countries.

The Observer has obtained electoral lists for Faridkot showing 478 registered voters, including a Mohammed Amir, married to Noor Elahi. Amir's and Noor's national identity card numbers have also been obtained. At the address identified in the list, a man identifying himself as Sultan said he was the father-in-law of Mohammed Amir.

A villager, who cannot be named for his own protection, said the village was an active recruiting ground for the banned militant group Lashkar-e-Taiba. 'We know that boy [caught in Mumbai] is from Faridkot,' he said. 'We knew from the first night [of the attack]. They brainwash our youth about jihad, there are people who do it in this village. It is so wrong,' he added.

According to the villager and other locals, Ajmal has not lived in Faridkot for about four years but would return to see his family once a year and frequently talked of freeing Kashmir from Indian rule.

The truth about Ajmal's origins are key to the ongoing investigation of where the attackers came from and will have a profound impact on relations between India and Pakistan. Islamabad has repeatedly said that no proof has been provided to back Indian accusations that all the gunmen came from Pakistan. The terrorist outrage has pushed the two nuclear-armed countries to the brink of confrontation but, until now, there had been no solid evidence that any of the militants were from Pakistan.

On Friday, police arrested two Indian men accused of illegally buying mobile phone cards used by the gunmen in the Mumbai attacks, in the first known arrests since the bloody siege ended. Security officials demanded the release of one of them, Mukhtar Ahmed, yesterday, claiming he was a counter-insurgency police officer who may have been on an undercover mission.

Police said another Indian citizen, Faheem Ansari, who was arrested in February in northern India carrying sketches of hotels, the train terminus and other sites that were later attacked, was being brought to Mumbai for renewed questioning.

Rakesh Maria, a senior Mumbai police officer, said he believed there was a connection between Ansari and the Mumbai attacks. 'Ansari was trained by Lashkar and sent to do reconnaissance,' Maria said.

One of the arrested men, Tauseef Rahman, allegedly bought Sim cards by providing fake documents, including identification cards of dead people, senior police official Rajeev Kumar said yesterday in the eastern city of Calcutta. Rahman, of West Bengal state, later sold them to Ahmed, Kumar said. Both men were arrested on Friday and charged with fraud and conspiracy.

Police said they were still investigating how the 10 gunmen obtained the Sim cards. Most large Indian cities, including Calcutta, where the Sim cards were purchased, have thriving black markets for Sim cards and cheap phones.

Ahmed was from the Indian portion of Kashmir, the disputed Himalayan region at the root of much of the tension between India and Pakistan, Kumar said. According to an unnamed police official in Srinagar, Kashmir's biggest city, Ahmed was a local police officer.