The formal communication was sent last night under the mutual legal assistance treaty signed by the two countries in 2005.
A government official said the trial court would take the call on the nature of their deposition depending on the response from Singapore.
In case there are practical difficulties in the doctors’ appearing in person, the court could agree to record their statement and allow the defence to cross-examine them through video-conferencing.
The Indian High Commission is in touch with the authorities concerned, the official said, pointing out that a response from Singapore was expected early next week.
Two AIIMS doctors -- who examined the five adult accused in the case -- had testified in the case last week. The doctors who examined the 23-year-old medical student at Safdarjung hospital are also prosecution witnesses.