Delhi police have arrested alleged Lashkar-e-Taiba (LeT) militant Abu Hamza, who is suspected of helping to plan the militant rampage through Mumbai in 2008 that killed 166 people, Foreign Minister S.M. Krishna said on Monday.
Authorities believe Hamza is the voice of a previously unidentified man who was taped speaking by phone from Pakistan to the militants involved in the Mumbai attacks. He is also said to have coached the attackers in speaking Hindi, according to the reports.
The 10 gunmen killed commuters, foreigners and some wealthy Indian businessmen in the rampage, which included attacks on two luxury hotels, a Jewish centre and a train station.
Peace talks between India and Pakistan have resumed since the attacks, but New Delhi still suspects Islamabad of dragging its feet in bringing the perpetrators to justice, a charge Pakistan denies.
"Let the Delhi police go through the investigation first, and then they will send a report to the government," Krishna told reporters, when asked how India would approach Pakistan over Hamza's arrest.
"And then we will certainly see what appropriate ... action can be taken," he said.
A Delhi police spokesman said he was not able to comment on the case.
Some local media reported that Abu Hamza had been deported from Saudi Arabia and arrested on landing at Delhi airport. Saudi Arabia's interior ministry was not immediately available for comment.
Public prosecutor Rajiv Mohan told Reuters that the suspect would be held in police custody for 15 days for questioning.
A voice believed to belong to Abu Hamza was recorded talking to the gunmen attacking a Jewish centre in south Mumbai during the three-day attack. According to the Times of India newspaper, he told the attackers to convey to the media that the "attack was a trailer and the entire movie was yet to come".
India has repeatedly called on Pakistan to take action against Hafiz Saeed, the Islamist blamed for masterminding the Mumbai attacks. In May, U.S. Secretary of State Hillary Clinton authorised a $10 million reward for information leading to his capture.