As many as 15 Israeli citizens may currently be held hostage in various locations around Mumbai following Wednesday's series of terror attacks.

The Foreign Ministry believes six Israelis are being held in the Chabad centre, with others among the hostages at the Oberoi Hotel.

A further 20-25 believed to be in the city have yet to make contact with their families in Israel.

Foreign Ministry officials described a tense and confused situation as they worked to gain information on the hostages and other Israelis.

Meanwhile, Defence Minister Ehud Barak spoke to India's National Security Advisor MK Narayanan to offer him Israel's assistance. "The attacks are part of a global wave of terror, which Israel is quite familiar with," he said.