Two FBI officers are expected to appear later before a special court in the Indian city of Mumbai to testify on last November’s attacks. Three other US nationals are also expected to give evidence, although using videoconferencing facilities.
More than 170 people were killed in the Mumbai attacks, nine of them gunmen.
Mohammad Ajmal Amir Qasab, a Pakistani national, faces 86 charges, including waging war on India, murder and possessing explosives.
After initially pleading not guilty, Mr Qasab confessed that he was one of the gunmen. The trial continues despite his admission.
Six of the people killed in the attacks were Americans, reports say.
“Two Federal Bureau of Investigation officers are likely to appear in person to tender evidence,” special public prosecutor Ujjwal Nikam was quoted as saying by the Press Trust of India.
The identities of the FBI officers and the American nationals have been kept secret for security reasons, the prosecutor said.
This will be the first time that witnesses from outside India testify in the Mumbai attack case.
Mr Nikam said the FBI officers were expected to tell the court about how the gunmen were in touch with their handlers during the attacks and the kind of technology they had used.
The attacks led to a worsening of relations between India and Pakistan.
India blamed Pakistan-based fighters from the banned militant group Lashkar-e-Taiba.
In the immediate aftermath of the killings, Pakistan denied any responsibility, but later admitted the attacks had been partly planned on its soil.
Islamabad also eventually confirmed that Mr Qasab was a Pakistani citizen.