New Delhi, Dec 17 - Left and BJP MPs in the Rajya Sabha Thursday sought a clarification from Prime Minister Manmohan Singh on the cooperation being provided by the US in unravelling the alleged involvement of Pakistan American David Coleman Headley in the 26/11 Mumbai terror attacks.

"I am sure the government will respond at the appropriate time," Chairman Hamid Ansari ruled as the prime minister who was present in the house gently nodded his head.

Speaking for the second time on the issue in the house, Communist Party of India-Marxist (CPI-M) member Brinda Karat said: "This is an issue that concerns all Indian citizens. I would request the prime minister for a clarification on what we are doing to take up the issue with the US."

Karat had earlier raised the issue on Tuesday speaking in similar vein.

Leader of Opposition Arun Jaitley (Bharatiya Janata Party) who raised the issue as soon as the house assembled also sought the response of the government on the Headley episode.

He also asked if there were differences between the ministries of external affairs and home on the issue. (IANS)