Patna, Jun 30 (IANS): Abductors of an engineering student from Bihar have demanded a ransom of Rs.20 lakhs to release him even as search operations have been intensified in the case, a police officer said here Saturday.

Ravi Kumar, a third year civil engineering student at the National Institute of Technology in Patna, was kidnapped June 23 from near his rented house here.

"Abductors called Ravi's family demanding a ransom of Rs.20 lakh for the student's safe release," the police officer said.

Search operations have been intensified and a suspect arrested in the case is being interrogated, he added.

"We have received two ransom calls in the last four days. Senior police officials were also present during the second call," a relative of the student told IANS over phone from Saharsa, around 240 km from here.

The kidnappers used Ravi's mobile phone to make the calls, police said.

"I am not happy with police investigation. They are clueless about my son," said Ravi's father Ramesh Razak, principal of a school in Madhepura district.

The abductors have threatened to kill Ravi if the ransom was not paid soon, Razak said.