The CBI on Monday opposed the bail granted to former Indian Air Force chief S.P. Tyagi in the Agusta Westland case.

The Central Bureau of Investigation told Justice I.S. Mehta that Tyagi, who is out on bail, might try to delay the case, and sought an early hearing.

The court posted the matter for hearing on January 18, after Tyagi's counsel urged more time to submit a response to the CBI petition seeking bail cancellation, and to an additional affidavit filed by the agency.

"It's a serious offence which has shamed the country. Accused (Tyagi) is out on bail. Every day is important in a matter like this...," Additional Solicitor General Tushar Mehta, appearing for CBI said, adding that case involved a multi-country probe.

"Several people involved in the case want to see that Tyagi is out (on bail)," Mehta added, while seeking an early court date for initiating arguments in the case.

The CBI told the high court that if Tyagi remained out on bail then he could try to hamper the investigation and tamper with the evidence related to the case.

The CBI challenged the trial court's order of December 26 that granted bail to Tyagi.

Tyagi -- the first chief of any wing of the armed forces to be arrested in the country -- and two others were allegedly involved in irregularities in the procurement of 12 AW-101 VVIP helicopters from Britain-based AgustaWestland.

He was the Air Force Chief from 2004 to 2007.

Tyagi remained in custody for 18 days. He was arrested on December 9, but later released on bail. The former IAF Chief has denied the charges of kickbacks.

Two other accused -- Tyagi's cousin Sanjeev Tyagi and Gautam Khaitan, a Delhi-based lawyer -- were released on bail on January 4, by the trial court.

The CBI had alleged that Tyagi and the other accused received bribes from AgustaWestland and helped the manufacturer win the $530 million contract to purchase the helicopters for the Communication Squadron of the Indian Air Force for ferrying the President, the Prime Minister and other VVIPs.

The probe agency had said the company was favoured in lieu of illegal gratification accepted through different companies in the name of consultancy services.

An FIR was registered against the accused on March 12, 2013, on charges of criminal conspiracy, cheating and under the Prevention of Corruption Act.