"It is difficult to give the exact number of Indians who have left so far as they are leaving from various airports apart from Tokyo. But the estimates are that the number at present is between 4,000 to 5,000," official sources told PTI.
They said the government was closely monitoring the situation in Japan, which is reeling under the devastation caused by the tsunami and earthquake on March 11.
"It is a fast evolving situation. No one can say what will happen in next 24 or 48 hours," they said.
The approximately 25,000 Indians in Japan were concentrated in the Kanto and Kansai regions.
Meanwhile, after the first consignment of relief material, comprising woolen blankets, sent to the devastation- hit country, India has offered to despatch a team of National Disaster Management Authority and a response from Japan is awaited.
Japan was hit by a massive earthquake causing giant tsunami waves and is currently struggling to avert a meltdown at a nuclear installation.