In a written reply to Leader of Opposition in the Rajya Sabha Arun Jaitley on the issue, the prime minister said the present incumbent of the Central Bureau of Investigation A.P.Singh is due to retire Nov 30. And even the government makes every effort to push the enactment of the Lokpal Bill, the premier investigating agency cannot be left without an administrative head in the meantime.

Under the circumstances the UPA government has in public interest made the appointment in accordance with the provisions of the CVC Act as presently applicable and the extant procedures, which had been set in motion much earlier, the prime minister said.

He also refuted suggestions by the opposition "that the appointments to this post in the past by the United Progressive Alliance (UPA) government were motivated by collateral considerations".

"In view of the above, the question of keeping the new appointment in abeyance does not arise," Singh said in his letter, according to a statement.

He began the letter saying that the Lokpal and Lokayuktas Bill 2011 is still awaiting passage in the Rajya Sabha. 

"The bill was referred to a select committee which has tabled its report today (Friday) in the Rajya Sabha. Many changes have been suggested by the select committee which are required to be considered by the government for introducing official amendments. After the bill as amended is duly passed by the Rajya Sabha, it will be returned to the Lok Sabha for further consideration," he said.

"In the meanwhile, the tenure of the present incumbent on the post of director, CBI is ending on 30 November, 2012, Even as we will make all possible efforts to enact the new law at the earliest, you would agree that a premier investigating agency like the CBI cannot be left without an administrative head pending the enactment," the prime minister said. 

"Under the circumstances the government has, in public interest, made the appointment in accordance with the provisions of the CVC Act as presently applicable and the extant procedures, which had been set in motion much earlier," he said.

The insinuation that the appointment was made to preempt the procedure recommended by the select committee is wholly unwarranted and devoid of any merit, Singh said in the letter.

"I also refute the suggestion that the appointments to this post in the past by the UPA government were motivated by collateral considerations," he said.

"In view of the above, the question of keeping the new appointment in abeyance does not arise," the letter said.

BJP leaders Sushma Swaraj and Arun Jaitley had written to the prime minister and said the government had chosen to appoint a new chief of the CBI hours before the select committee on Lokpal tabled its report in the Rajya Sabha.

Sinha was Thursday appointed as the next director of the CBI for a two-year term.