The Indian government has not been able to make contact with 40 Indian construction workers in the Iraqi city of Mosul, with one leading Indian newspaper reporting that they have been kidnapped.

Foreign Ministry spokesman Syed Akbaruddin said dozens of Indian workers were living in areas overrun by the Islamic State of Iraq and the Levant (ISIL), and India was in contact with many of them, including 46 nurses. It has sent a senior envoy to Baghdad to support repatriation efforts.

“There are also reports which have been brought to the notice of our embassy that there are 40 Indian nationals in Mosul,” Akbaruddin said.

“Despite our best efforts at this stage, we haven’t been able to contact them. So they remain uncontactable.”

Akbaruddin said the government had no “confirmation or verification” of a story in the Times of India newspaper that the construction workers were being held by suspected ISIL fighters.

The nurses are stranded in Tikrit, which is under militant control, with many of them holed up in the hospital where they work. Nurses who spoke to the Indian media said they had been treating people injured in fierce street fighting.

Humanitarian group the Red Crescent has contacted the nurses and is providing assistance, Akbaruddin said.

ISIL fighters, who aim to establish a Muslim caliphate across the Iraqi-Syrian frontier, launched their revolt by seizing Mosul, and swept through the Tigris valley towards Baghdad.

Scores were killed on Tuesday in a battle for a provincial capital close to Baghdad, and fighting shut Iraq’s biggest refinery at Baiji, hitting fuel and power supplies.