The new archbishop of Warsaw has assumed his duties, three months after his predecessor admitted to being a communist-era informer and resigned.

More than 1,000 people attended Palm Sunday Mass today in Warsaw, where a Papal decree was read appointing Kazimierz Nycz, a former bishop in northern Poland, to the post.

Pope Benedict XVI appointed the cleric last month, after his previous choice, Stanislaw Wielgus, resigned, admitting he had worked with Poland's dreaded communist-era police for two decades beginning in the 1960s.

In his admission, Wielgus expressed remorse and said he never informed on or sought to hurt anyone.

Polish President Lech Kaczynski and his brother Jaroslaw, the prime minister, have vowed to root out those in public life with close ties to the communist apparatus.

Some information for this report was provided by AFP and AP.