Updated

Poland's Foreign Ministry says Russia has arrested three Polish journalists at the site of a plane crash where President Lech Kaczynski and 95 others died in April.

Ministry spokesman Marcin Bosak says the three were detained Friday by the Russian army for entering twice onto restricted military grounds, and are being questioned.

The incident threatens to raise tensions between Poland and Russia, Slavic neighbors that have had difficult relations since Poland broke away from Moscow's sphere two decades ago to chart a Western course.

An official at the Polish embassy in Moscow, Pawel Koc, called the matter "serious."

The all-news station TVN24 said one of its reporters was among those arrested, and that the group had been observing and filming the wreckage.