New Delhi, April 25 (IANS) Angry opposition parties have vowed to cripple parliament Monday over a report claiming the government had tapped the telephones of key political leaders, including from the Congress and its ally the Nationalist Congress Party (NCP).

The Bharatiya Janata Party (BJP) accused the Congress of taking India back to the "Emergency" days of 1975-77 by reportedly ordering the tapping of the phones of Bihar Chief Minister Nitish Kumar of the Janata Dal-United (JD-U), Congress general secretary Digvijay Singh, Agriculture Minister and NCP leader Sharad Pawar and Communist Party of India-Marxist (CPI-M) general secretary Prakash Karat.

The CPI-M, in a statement Saturday, asked the government to own up responsibility in the matter and take action against those who ordered the surveillance.

"Protecting the covert activities of the intelligence and security agencies cannot be made the pretext for a cover-up," the CPI-M said, referring to the revelations in the newsmagazine Outlook.

"The report shows that the government is using the intelligence and security agencies to serve its political purpose to spy upon opposition leaders and to keep track of even its own allies and party leaders," the CPI-M said.

The Outlook expose comes at a time when the Congress is already battling the Indian Premier League (IPL) cricket storm that has led to the exit of one minister and cast a shadow on two others, including Pawar, and ahead of crucial voting in parliament on the national budget for 2010-11.

The opposition has been threatening to introduce cut motions in the Lok Sabha in a bid to defeat the finance bill, a development that could seriously embarrass the Congress-led government.

The BJP accused the Congress of going back to the "Emergency" rule of then prime minister Indira Gandhi when scores of opposition leaders were jailed and democratic rights were curbed.

"This is completely undemocratic. Nothing justifies it. It indicates the Congress is getting back to the Emergency days mindset," BJP spokesperson Nirmala Sitharaman told IANS.

Sitharaman said the BJP planned to raise the issue when parliament meets Monday.

The government has not commented on the Outlook report so far. The Congress has come out with a guarded reaction, saying it was for the government to say if phones were tapped and whether it was legal.

"Nobody can justify illegal phone tapping, but in this case it is for the government to throw light on whether phones were tapped," Congress spokesman Shakeel Ahmed said.

Pawar's NCP, a key member of the UPA government, was also guarded. "It (phone tapping) is not confirmed yet. Wait for some concrete evidence," NCP leader Tariq Anwar said.

Nitish Kumar reacted angrily in Bihar. "Are they going to tape phone conversations of every person in politics they are uncomfortable with. Who has given them the right to tap phone conversations," Kumar said, adding, "I want to know one thing, are they so much troubled by a person like me that they need to tap my phone. Am I a threat for national security?"

His JD-U colleague, Rajya Sabha member, Ali Anwar Ansari, said: "It is murder of democracy." He said the party would strongly raise the issue in parliament Monday.

Rashtriya Janata Dal (RJD) leader Lalu Prasad said that though phone tapping was wrong, Kumar should not be worried about it if he had not done anything wrong.

Congress general secretary Digvijay Singh, speaking in Panchkula, Haryana, said he does not believe the "story" of phone-tapping, "because Manmohan Singh's government cannot do such an unethical and illegal task".

However, he added that since the "story has come, it should be inquired into".