"The UPA government must bring a strong Lokpal bill in the session from August one and the Prime Minister must be under its ambit," CPI(M) Secretary Parkash Karat told reporters here.
"The Left is of a strong opinion that the Prime Minister must be under the Lokpal," he said.
He said the Lokpal drafts presented in parliament in 1989, 1996, 1998 and 2001 had included the Prime Minister.
Questioning why the UPA government was shying away from bringing the Prime Minister under the anti-graft bill, Karat said, "The Prime Minister is under the ambit of Prevention of Corruption Act... so he should be brought under the Lok Pal bill as well."
He, however, said that higher judiciary -- judges of Supreme Court and High Court-- should be kept out of the Lokpal Bill.
Stating that corruption "exists" in judiciary as well, he mooted setting up of National Judicial commission to check the menace
On the cash-for-vote scam, he alleged that as many as 19 MPs were bribed after the Left withdrew support to the Congress-led UPA in 2008.
Karat said that the Delhi Police should not confine its investigations to the three BJP MPs, who had made the allegation, rather it should probe the role of all the 19 MPs.