New Delhi, Dec 4: A Kanpur-bound 'Indian' aircraft with 42 passengers on board today returned here after police in the Uttar Pradesh city received a phone call threatening that it would be hijacked.

All passengers were safe and searches on the plane were on, sources said. The plane landed at the Delhi airport soon after take-off as Kanpur police informed authorities about the phone call threatening that it would be hijacked, the sources said.

The unidentified caller also claimed that bombs had been placed in the plane, they said.

Soon after the information was passed over to Delhi airport, anti-hijack and anti-sabotage measures were initiated, a senior airport official said.

The plane landed under full emergency conditions, they said adding passengers were thoroughly checked.

The caller, who is yet to be identified, also tried to raise a bomb scare, saying an explosive had been planted in the plane. Anti-hijack and anti-sabotage teams immediately sprang into action the moment they got the information about the ''possible hijack''.

All the passengers were safe and thoroughly checked after the plane made an emergency landing, the official added.