Two sons of a Delhi-based contractor who provided manpower to big construction companies were allegedly kidnapped after landing in Patna on Friday evening to take part in a construction tender.

The police denied ransom as the motive behind the kidnapping of Suresh Sharma, 40, and his younger brother, Kapil Sharma, 27 from the VIP area, which houses several ministers and senior bureaucrats<>.

The incident came to light on Saturday when the boys' father, Babulal Sharma, arrived from Delhi and lodged a complaint with the airport police station.

He said his sons informed him over phone that they had been kidnapped.

Patna senior superintendent of police (SSP) Manu Maharaaj said the brothers had been invited by an acquaintance to take part in a tender for construction-related work in Munger. The acquaintance had provided air tickets for the trip to Patna and received them when they arrived around 6.30pm on Friday by a GoAir flight.

The plan was to stay in Patna for a while and then set off for Munger. Before setting off for their destination in an SUV, one of the brothers told the family they were fine.

When their father called around 9.30pm, they said they were on the road but called back two minutes later to say they had been kidnapped. Repeated calls after that went unanswered till the phones were switched off around 11pm. "Their phones are switched off since 11pm on Friday," the SSP said.

Maharaaj outrightly denied the two had been kidnapped for ransom. "We have got some clues and efforts are on to rescue them," he said on Sunday.

Earlier, inspector-general (Patna zone) Nayyar Hasnain Khan said a police team headed by the Patna SSP had been assigned the case.

The police have zeroed in on members of a gang. Call detail records of the cellphones of the captives have been procured. "We can't share details as human lives are involved," the inspector-general said.

The Sharmas hail from Rajasthan and are settled in Delhi's Badarpur area. They are also into marble trade in Lucknow. An investigating officer said on condition of anonymity that the brothers' Facebook accounts suggest they were in touch with the acquaintance (now suspect in the kidnapping case) for long. Even their father Babulal was aware of this, the officer said.

A criminal gang operating from Lucknow's Gomati Nagar area was on the police radar although both the family and police denied any ransom had been sought.

A Thane-based realtor, Khalid Qadri, was kidnapped in a similar manner from outside Patna airport on July 30. He was released near the border with Nepal at Raxaul in East Champaran district on August 5, allegedly after Rs 30 lakh was paid in ransom. Bettiah police later arrested Noor Alam, Safiullah Khan and Irfan Khan from the house Qadri was confined in and recovered Rs 29.89 lakh. Khalid's wife Shama Qadri had come from Thane with the ransom.

"There is a professional gang in Patna, which adopts this modus operandi to target big traders and other professionals," an IPS officer adept in handling such cases told The Telegraph.