German Chancellor Angela Merkel's backing of French President Nicolas Sarkozy in the upcoming presidential vote has riled his socialist rival Francois Hollande's camp, which warned her to exercise restraint, a German newspaper reported on Saturday.
It is unusual for German leaders to intervene in elections abroad. Merkel's backing for Sarkozy was announced in January by her Christian Democrat (CDU) party, whose second-in-command Hermann Groehe said Hollande's policies would weaken Europe.
Party politics should not weigh on the future relationship, Pierre Moscovici, campaign chief for Hollande was quoted as saying by German weekly Frankfurter Allgemeine Sonntagszeitung in an article due to be published on Sunday.
The chancellor is obliged to show a certain reserve.
Insiders at Sarkozy's UMP party say the push to involve Merkel came from the French president himself, who is lagging behind in polls ahead of the two-round election on April 22 and May 6.
The German chancellor is seen in France as a trustworthy leader capable of dealing with the euro zone debt crisis, and so could boost Sarkozy's credibility on economic issues.
But the move could also backfire if voters view her involvement as unwelcome interference, and some of the austerity policies she has pushed for have been unpopular in Europe.
Merkel's party has said she plans campaign appearances with Sarkozy in a move aimed at underlining the importance of the two leaders' relationship to Europe.
A poll this week showed Hollande had widened his lead over Sarkozy.
(Writing by Brian Rohan; Editing by Alessandra Rizzo)