By Erik Kirschbaum
BERLIN, Feb 15 (Reuters) - Conservative allies of German Chancellor Angela Merkel rebuked their Social Democrat governing partner on Saturday over actions that led to the ouster of a minister, deepening concern about the future of her two-month-old "grand coalition".
Friday's resignation of Agriculture Minister Hans-Peter Friedrich, the latest in a series of cabinet departures under Merkel, could aggravate tensions in Berlin's coalition at a time when it is trying to push through complex reforms of pensions and renewable energy.
Horst Seehofer, head of the Christian Social Union, arch-conservative wing of Merkel's Christian Democrats, demanded explanations from the Social Democrats after CSU member Friedrich quit over accusations he leaked confidential data.
The information derived from a prosecutor's investigation into an SPD lawmaker suspected of possessing child pornography. The lawmaker, Sebastian Edathy, has denied the accusations.
Merkel's governing "grand coalition" is under serious strain and could even be in jeopardy if the scandal undermines the position of SPD chairman Sigmar Gabriel, who was tipped off about the investigation by then-interior Friedrich in October.
What began as a small domestic scandal about Edathy erupted into a major political furore when the SPD said Friedrich had warned Gabriel that Edathy could become a target of an investigation.
That raised questions whether Friedrich had inappropriately passed on confidential information about the looming investigation to Gabriel in violation of the law. Gabriel said he alerted two other SPD leaders.
Friedrich was on his way home to Bavaria on Friday when Merkel called him and told him to return to Berlin to announce his resignation, the Bild and die Welt newspapers reported.
Political scientists and columnists said Merkel might have sacrificed Friedrich, a senior figure in her conservative block, to prevent further damage to Vice Chancellor Gabriel, who is the SPD chairman and a pillar of her grand coalition.
Merkel's government could be doomed if the scandal damages Gabriel or forces him to resign. At the very least it could be a distraction to Economy Minister Gabriel as he tries to push through complex energy reforms that Germany urgently needs.
"I demand that the SPD clear up their contradictions this weekend," Seehofer, the Bavarian state premier, told CSU party members in Bamberg. "There's a need to talk about their behaviour and actions. It's a big problem when someone breaks their word of confidentiality."
Angry that his CSU minister had to resign, Seehofer said he backed Friedrich's position that he told Gabriel about the Edathy investigation in the spirit of cross-party cooperation as the grand coalition was being formed.
"Friedrich acted in the best interest of the entire grand coalition," Seehofer said, adding he was especially upset that some SPD deputies demanded Friedrich resign. "The actions of the SPD and their talkativeness can only be condemned."
Prosecutors in Hanover, who are investigating Edathy, have complained that the leaking may have compromised their case. Edathy appears to have been given advance warning of the investigation, Hanover prosecutor Joerg Froehlich said.
The 44-year-old Edathy is well known in Germany for leading a 2012-13 inquiry into neo-Nazi killings.