The Central Bureau of Investigation (CBI) launched raids in New Delhi and Chandigarh on Wednesday after formally launching a probe into the AgustaWestland bribery case. Former Indian air force chief S.P. Tyagi was among 12 individuals being investigated.

The CBI said it had registered a criminal case under India's anti-corruption laws and named Italian defence company Finmeccanica and its Anglo-Italian unit, AgustaWestland, as targets of its probe.

It said in a statement that four firms and 12 individuals, including former Indian air force chief S.P. Tyagi, were being investigated. Searches were under way at 14 locations.

"The CBI has launched raids across 14 different locations in Chandigarh, Delhi, Mohali and Gurgaon on offices and homes of the people against whom the investigations are being conducted," CBI spokeswoman Dharini Mishra said.

Helicopter company AgustaWestland has denied paying bribes in a $750 million deal to supply a dozen AW 101 helicopters for Indian political leaders. Italian police have arrested the head of Finmeccanica, Giuseppe Orsi, in connection with the case.

India has asked AgustaWestland to explain accusations by Italian prosecutors that millions of euros in kickbacks were paid through middlemen to clinch the deal. It has also frozen payments for the luxury helicopters pending an inquiry by the CBI and has said it is seeking to cancel the deal.

In recent years, India has emerged as the world's largest weapons importer, but procurements are periodically held up by allegations of corruption. Finmeccanica could be blacklisted in India for at least five years if investigators prove bribery.