Overlooking US envoy's remarks here that no decision has been taken for giving Indian investigators direct access to David Headley, India on Tuesday said it will soon write to the US for interrogating the LeT terrorist.

The home ministry will soon communicate to the US Department of Justice seeking a date for having direct access to Headley, currently under American custody, top government sources said.

The decision comes close on the heels of Government stating that it was not taking cognisance of the clarification issued by US Ambassador to India Timothy J Roemer that no decision has been taken and the US has yet to work out how India would be given access.

In its communication, likely to be finalised in the next few days by home minister P Chidambaram and top officials, the ministry will tell the American authorities that a team of Indian investigators was ready and it could visit the US once a confirmation is given.

The sources said the National Investigation Agency (NIA), probing the case of the 49-year-old terrorist who has admitted to plotting the audacious Mumbai terror attack in November, 2008, will file the charge sheet against him only after getting direct access to him.

According to the American law, the US Department of Justice will have to take permission from the Chicago court, which is hearing Headley's case, about India's request to have direct access to him.

In London, Chidambaram said he does not think there has been a "turn around" by the US on the issue of Indian investigators getting direct access to Headley, a Pakistani- American LeT operative.

"No, I don't think so," he said when asked by reporters whether there was a turn around by the US.

"... If you reflect more carefully that sentence (of Roemer) no way (it) contradicts what the US Attorney General (Eric Holder) has told me," Chidambaram, who is on an official visit, said.

"It is my understanding that India would be able to obtain access to Headley to question him in a properly- constituted judicial proceeding. Such judicial proceeding could be pre-trial or during an inquiry or trial," the Home Minister had said in a statement on Saturday after a telephonic talk with Holder.

Special secretary (internal security) U K Bansal last night met Solicitor General Gopal Subramanium here and discussed with him about the options available before Indian investigators to question Headley under the plea bargain agreement between him and the American government.

Sources said investigators believe that access to Headley can be obtained only through legal channels as he is under court's custody.

Under the plea bargain, India can have access to the terrorist by deposition, video conferencing or through Letters Rogatory. Sources said India will like to explore all the three.

Headley had last week pleaded guilty to all the 12 terror charges of conspiracy involving bombing public places in India, murdering and maiming persons and providing material support to foreign terrorist plots and Pakistan-based LeT besides aiding and abetting the murder of six US citizens in the 26/11 attacks that killed 166 people.

Headley was arrested by the FBI in October last year.

In Chicago, Headley's lawyer John Theis said his client will cooperate with Indian authorities as required under the terms of his plea agreement if the US government allows.

Theis said the terms of the plea agreement on March 18 requires that he allows himself to be interviewed by Indian authorities.

"Headley will cooperate to the extent it is required to by the terms of his plea agreement but as for the specifics, I think really our government and our US attorney's office have to be the ones to determine the actual form (of access)," he told PTI when asked to comment about Roemer's statement.

"He is in US custody and so interviewing him does implicate the security issues and things like that," Theis said.

When asked if Indian investigators, who come to the US, can be assured that they would get access to Headley and be able to put their questions to him, Theis said: "I'm not the one to ask that. You will have to ask our government, our US attorney's office. They are the ones who are going to determine how this actually happens".

An FBI spokesperson told PTI, "If the plea agreement says that Headley has agreed to meet with investigators from India, then that is what he will do. It is a question of when and where.

Following discussions with Holder, Chidambaram had directed National Intelligence Agency and other agencies concerned in the case to quickly prepare documents necessary to start a judicial proceeding in which Indian authorities could require Headley to answer questions and to testify.

India is likely to send a team of investigators in April to question Headley.