India's foreign minister told parliament on Tuesday he was "deeply concerned till law and order is visibly restored" in neighbouring Bangladesh, a day after the ouster of prime minister Sheikh Hasina.

Foreign minister S. Jaishankar also gave the first official confirmation Hasina was in India where she fled to on Monday as protesters stormed her palace.

"We ... will naturally remain deeply concerned till law and order is visibly restored," Jaishankar said.

New Delhi has kept a wary eye on the fall of Hasina, who pursued a delicate balancing act of enjoying support from India while maintaining strong relations with China.

Bangladesh army chief General Waker-Uz-Zaman announced Monday afternoon on state television that Hasina had resigned and the military would form an interim government.

"In the last 24 hours, we have also been in regular touch with the authorities in Dhaka," Jaishankar added.

Hasina fled Bangladesh on Monday by helicopter to India, arriving at a military airbase near New Delhi.

A top-level source said she wanted to "transit" on to London, but calls by the British government for a UN-led investigation into "unprecedented levels of violence" put that into doubt.

"Our understanding is that after a meeting with leaders of the security establishment, Prime Minister Sheikh Hasina apparently made the decision to resign," Jaishankar said.

"At very short notice, she requested approval to come for the moment to India. We simultaneously received a request for flight clearance from the Bangladesh authorities. She arrived yesterday evening in Delhi."

India shares a more than 4,000-kilometre (2,545-mile) border with Bangladesh.

"Our border guarding forces have also been instructed to be exceptionally alert in view of this complex situation", Jaishankar said.