The Pakistani probe team has already arrived in India to probe the Pathankot airbase attack in Punjab, an official said.
Punjab counter-terrorism department chief Muhammad Tahir Rai, who heads the high-powered Joint Investigation Team (JIT), has reached India along with some other officials, The Nation quoted a senior official as saying on Thursday.
A JIT formed on the orders of Pakistani Prime Minister Nawaz Sharif formally started working last week, and its first meeting was convened in Lahore to discuss the case in detail, the report said.
The Punjab province home department on Thursday also re-notified the JIT, ordering the investigators to submit the interim probe report to the court within two weeks.
It was not clear if there was any change or the new notification retained the same members as that of the earlier JIT, which was constituted by the interior ministry in mid-January.
A provincial government official confirmed that Tahir Rai, who is additional inspector general of police, has arrived in India and this move is being kept secret on both sides of the border.
"What I can confirm is that Rai is in India right now. We can't tell how many officials accompany him," the official said on the request of anonymity.
The official did not comment on the day the team left for India to probe the attack and for how many days it would be there.
Jaish-e-Muhammad (JeM), a Pakistani militant outfit, was responsible for the attack on the airbase in Pathankot town on January 2.
As many as seven security personnel were killed in the attack. The security forces also killed all six terrorists in over three days' operation.
New Delhi said the fate of 'comprehensive dialogue process' -- started by both the countries recently to improve India-Pakistan ties -- depended on Islamabad's action against the perpetrators of the attack.
Pakistan registered a case on the basis of leads provided by India and formed an investigation team comprising high-ranking officials of police and intelligence agencies.
The counter-terrorism department (CTD) of Pakistan's Punjab province on Thursday lodged a case against six "non-state actors" for plotting the attack.
Official sources in the Punjab home department said the JIT members during their visit to India would collect facts about the Pathankot attack.
However, no information was provided weather the investigators was allowed to visit the Indian airbase as earlier New Delhi denied the team access to the airbase.
One official said the team would also discuss modalities for carrying out joint investigations with their Indian counterparts.
"Although no timeframe has been given to complete the probe, it is expected that the team will complete the investigations within 15 days," another official said.
"If the probe remains incomplete after two weeks, the JIT may seek more time from the court since it is a matter of criminal procedure code."
Earlier, four suspects were detained in connection with the phone numbers mentioned in the first information report.
The investigators were examining the SIM registration and call data of the numbers. The mobile phone companies were asked to provide details of the persons using those phone numbers.
