India yesterday made it clear that foreign secretary-level talks with Pakistan will go ahead only if Islamabad acts on the 'actionable intelligence' provided by Delhi on the Pathankot terror attack.

"The ball is in Pakistan's court," External Affairs Ministry spokesman Vikas Swarup said when

India-Pakistan relations saw a new hope when Prime Minister Narendra Modi made a surprise visit to Lahore to meet Nawaz Sharif. PM Modi's surprise visit created goodwill and there were signs of forward movement in bilateral relations.

However, the Pathankot terror attack has once again put the focus on terror.

Meanwhile, Indian intelligence agencies have identified Jaish-e-Mohammad chief Maulana Masood Azhar as the prime mastermind of the air base terror attack.

India has also shared with Pakistan the identity of four Jaish-e-Mohammad (JeM) handlers suspected to have guided the Pathankot attackers.

Modi on Tuesday urged his Pakistani counterpart to take "firm and immediate action" against those behind the attack, adding that New Delhi had passed on "specific and actionable information" about the incident, reports AFP.

Pakistan PM Nawaz Sharif yesterday chaired a high-level meeting and discussed the terror attack as he directed officials to speed up work on the leads given by India, sources said.

Reports suggest that a large group of infiltrators was tracked across the border around the suspected time of infiltration by the Pathankot attackers. "We fear the group that infiltrated was much larger than just 5 to 6 people. We fear they may have travelled further after crossing the border, including to Delhi where they may strike around the Republic Day," said an officer.

"We have already alerted the Delhi Police and other agencies. The security for this year's Republic Day celebrations will be of the highest level, possibly as tight as last year when US President Barack Obama was the chief guest for the parade," said the officer.