Berlin  - The unexpected resignation of Germany's economics minister has revealed stress fractures in Chancellor Angela Merkel's unhappy political alliance.

The resignation tendered by Economics Minister Michael Glos comes just months ahead of general elections due September 27, and in the midst of an unprecedented global financial crisis.

Glos, who is 64, said at his age he no longer sought a position in a new post-September government. It's no secret however that there were strains in his relationship with Bavaria's premier, Horst Seehofer.

Both men are leading figures of Bavaria's conservative Christian Social Union (CSU, whose alliance with Chancellor Angela Merkel's Christian Democrats (CDU) makes up a sizeable proportion of the conservative camp's national support.

Just over three years after being shoehorned into a job intended for Bavaria's then premier Edmund Stoiber, Glos announced Saturday that enough was enough.

Seehofer confirmed Glos' resignation Monday at a press conference in Munich, revealing at the same time the ministerial appointee who would fill the gap.

He spoke openly of Saturday's unexpected, and "unhappy developments" that had distracted him from an annual security conference in Munich and his international guests, who included new US Vice President Joe Biden.

Glos' decision had reached Seehofer via media reports, sending him scrambling frantically for the resignation letter waiting at his home address.

The Bavarian premier initially countered Glos' request with an equally unexpected "no," but changed his mind over the course of the weekend.

In light of the pressing demands of the international security conference, Seehofer had said he "couldn't meet" the request, adding that Glos should stay in office until the general election.

A series of consultations followed within the CSU and at national level with Merkel and the CDU, and a successor was found Sunday in Karl-Theodor zu Guttenberg, a
37-year-old aristocrat who has been rising rapidly through the CSU party ranks.

The terms of the CDU-CSU alliance grant Bavaria's CSU the right to nominate the country's economics minister.

Zu Guttenberg was first elected in 2002 as a member of parliament in Berlin and promoted 2008 to become the CSU's general secretary in Munich.

He had barely completed 100 days in this role, when the decision was made Sunday to nominate him as Glos' successor.

With a keen eye on the September elections, zu Guttenberg has little time to make the most of this unexpected opportunity and prove himself on the national stage.

His combination of foreign affairs experience, media acumen and political hunger will make him a figure to be reckoned with in the coming months.

Both Merkel and Finance Minister Peer Steinbrueck of the centre- left Social Democrats (SPD), currently managing the financial crisis between them, will likely notice the eager snapping at their heels as the electoral clock ticks towards September 27.

The SPD has spoken critically of the weekend's political circus. General secretary of the SPD, Hubertus Heil, called the CDU-CSU infighting an "undignified game."

"To me, this is a symptom of a crisis," Heil said, adding that Merkel needed to keep Seehofer in check.

SPD leader Franz Muenterfering said Glos had been treated unfairly by his own party.

"If you want an economics minister to act more strongly than he did at such a crucial time, you need to support him, rather than saw off the legs of his chair from behind," Muenterfering said Monday.

Head of the liberal Free Democrats (FDP), Guido Westerwelle, described the weekend's events as "clownery", giving the impression that Merkel "evidently has little authority."

"The confusion is bad for our country," Westerwelle said, adding that Germany couldn't afford this during the current economic crisis.

In recent months Seehofer's Bavarian CSU party has been criticized for throwing its weight around.

A proposed environmental law was recently deemed to have failed owing to Bavarian stubbornness, and new federal budget regulations only got the CSU's green light at the last minute. dpa