Updated

Germany's 2-month-old government is facing its first serious test, after old enmities between Chancellor Angela Merkel's conservative bloc and their center-left coalition partners flared over the handling of a child pornography investigation.

The deputy leader of Merkel's Christian Democratic Union, Armin Laschet, called Sunday for senior Social Democrats to state "under oath" that they didn't warn one of their party's lawmakers that he was under investigation for allegedly possessing pictures of underage boys.

Laschet's demand is directed at Economy Minister Sigmar Gabriel, Foreign Minister Frank-Walter Steinmeier and the Social Democrat's parliamentary leader, Thomas Oppermann.

Conservative Cabinet minister Hans-Peter Friedrich resigned Friday after acknowledging that he passed information on the case to the Social Democrats' leadership.

The case is likely to dominate a meeting of the coalition parties on Tuesday.