The interrogation started around 4 a.m. soon after they were brought to its office here, a senior ED official said.

Both would be produced before a court around 2 p.m. and the agency would seek their custody for questioning in two separate cases, he added.

The extradition comes as a major boost to the Indian agencies investigating corruption angles in two separate cases involving the two.

According to sources, a two-member ED team headed by an Inspector General rank officer and officials of Ministry of External Affairs and Research and Analysis Wing (R&AW) accompanied both the accused to Delhi from Dubai in the aircraft which landed at the Indira Gandhi International (IGI) Airport here around 2.30 a.m.

Soon after the aircraft landed, Talwar and Saxena was taken into ED custody. After completing the immigration process and medical examination, they were moved to the ED's Jamnagar House office here.

While Talwar was later taken to ED headquarters in Khan Market area, Saxena was taken to MTNL building on Janpath, here.

On Wednesday, Saxena was reportedly picked up by the UAE security authorities from his residence and extradited to India in the evening for his pivotal role in laundering the money received to pay kickbacks in the Rs 3,600 crore AgustaWestland chopper deal scam.

The agencies also brought corporate lobbyist Talwar to India as he fled to Dubai after the Indian agencies started probing his role for concealing income of more than Rs 1,000 crore as well as facilitating aviation contracts during the United Progressive Alliance's (UPA) regime.

He is accused of brokering aviation sector deals, getting government approval for foreign companies, securing favours for clients and having ties with UPA functionaries.

In Saxena's case, the ED in its supplementary charge sheet had elaborated on how the bribe money paid to clinch the AgustaWestland chopper deal was "layered" and projected as "untainted money" by creating "fictitious invoices".

It has also mentioned how fictitious engineering contracts were created to hide the kickbacks allegedly paid by AgustaWestland to companies directly controlled by lawyer Gautam Khaitan -- now in ED custody -- and his associate Saxena.

A Delhi court had issued a non-bailable warrant against Saxena, the Dubai businessman, after it came to know that he had not joined investigation despite repeated summons against him.

Saxena's name was mentioned in a charge sheet filed against his wife, Shivani, who has been out on bail after being arrested by the ED.

Saxena was named only in the third supplementary complaint filed in July 2018. The same is also under challenge before the Delhi High Court by another accused in the case, Khaitan.

The ED had earlier arrested Saxena, the Director of Matrix Holdings Dubai, under the Prevention of Money Laundering Act in connection with the case.

The Indian government had on December 4, 2018, extradited one of the key middleman Christian James Michel, a British national from Dubai.

On January 1, 2014, India cancelled the contract with Finmeccanica's British subsidiary AgustaWestland for supplying 12 AW-101 VVIP choppers to the Indian Air Force (IAF) over alleged breach of contractual obligations and on charges of paying kickbacks amounting to Rs 423 crore.