As speculation mounts on the equation between Finance Minister Pranab Mukherjee and Home Minister P. Chidambaram, who has been named in the 2G scam, Congress chief Sonia Gandhi has directed top leaders to put up a joint defence, party insiders said.

Gandhi, who has recently returned after a surgery abroad, is learnt to have stepped in to resolve the crisis involving one of the government''s most high profile ministers.

The controversy surfaced after a RTI answer revealed that the finance ministry - headed by Mukherjee - had sent a note to the Prime Minister's Office (PMO) in March 2011 that 2G spectrum licences would have been auctioned in 2008 if then finance minister Chidambaram had acted.

This has led to the opposition asking for Chidambaram's resignation and speculation that things are not as they should be between the two ministers.

"Soniaji has asked all top leaders - from Prime Minister Manmohan Singh to party spokespersons - to defend Chidambaram and the government," a senior Congress leader told IANS on condition of anonymity.

"She knows that this is an explosive issue. Yesterday it was A. Raja and Dayanidhi Maran (ministers who had to quit over the 2G spectrum row), today it is Chidambaram and tomorrow it can be Manmohan Singh. She wants to stop the slide," he added.

Corporate Affairs Minister M. Veerappa Moily's strong defence of Chidambaram Friday and the home minister's statement that he would not comment on the issue till the prime minister returns from his foreign visit are learnt to have been directed by Gandhi.

The Bharatiya Janata Party (BJP) and the AIADMK have launched a vehement attack on the government and demanded Chidambaram's resignation.

Though Congress leaders deny talk of a Mukherjee-Chidambaram rift being the root cause behind the controversial note, political analysts and party insiders say there is a "recurring cold war" between the two.

"The rivalry between the two financial wizards have been escalating in the past two years. Soniaji was aware of the issue and had intervened to defuse the situation occasionally," said a Congress leader.

"The cold war has been surfacing through various incidents and on different occasions. A major incident was when Mukherjee confirmed June 22 that he had suspected that his finance ministry offices were bugged in September 2010 and had sought a secret inquiry," said an analyst.

The needle of suspicion then had pointed to intelligence agencies controlled by Chidambaram's home ministry.

Supporters of Mukherjee are believed to have told Gandhi that the veteran leader's trouble-shooting capabilities and political skills were often ignored and "administrative tough actions" advocated by Chidambaram were enforced, leading to fresh crises.

"The latest example was the handling of the fast by civil society leader Anna Hazare in August," said another party leader.

He said Hazare was arrested Aug 16 on the direction of Chidambaram, prompting massive protests that led to the activist being released.

The group of ministers led by Chidambaram, who were handling the Hazare fast, was replaced by a team led by Mukherjee and Law Minister Salman Khurshid. The new team could broker peace and end the 10-day-old fast by Hazare, the Congress leader added.

Kerala-based political analyst B.R.P. Bhaskar told IANS that the Mukherjee-Chidambaram rift may continue till Rahul Gandhi takes a more leading role in the Congress.

"Some infighting had been common in Congress... With a member of the Nehru-Gandhi dynasty usually on the top slot earlier, the fight had been for the second or the third place.

"But now it is different. With Sonia Gandhi recuperating and Rahul Gandhi yet to take over the top post in the party or the government, several leaders and ministers will be working against each other," Bhaskar told IANS over the phone.