New Delhi: The Enforcement Directorate (ED) on Friday issued summons to ex-IAF chief S.P. Tyagi as part of its ongoing probe in the AgustaWestland choppers deal.

He has been summoned under the Prevention of Money Laundering Act. However, the date of hearing has not been revealed.

The ex-IAF chief is accused of modifying the requirements in order to seal the deal with AgustaWestland.

Meanwhile, James Christian Michel, the accused middleman in the chopper deal, has offered himself up for questioning by the Enforcement Directorate and the Central Bureau of Investigation (CBI).

AgustaWestland's Rs 3,600 crore contract for supplying 12 VVIP choppers to the Indian Air Force was scrapped by the UPA government over charges of paying kickbacks to Indian agents.

In January 2013, India cancelled the deal and the CBI was assigned to investigate the matter.