WARSAW, Poland (AP) — Poland has until Saturday to explain to European Union authorities why it has increased logging in one of Europe's last primeval forests and to suspend the excessive removal of trees, environmental groups said Friday.

The European Commission, the EU's executive arm, says the logging in Bialowieza Forest violates EU laws and threatens the UNESCO World Heritage site. It is threatening to take the Polish government before the EU's Court of Justice, if it does not comply by the deadline.

Bialowieza is a relic of an ancient forest that once stretched across Europe's lowlands. Its oldest section, a dense, mossy woodland, is home to bison, lynx, storks and other animals.

The ancient forest, which straddles Belarus and Poland, is recognized by the United Nations as a natural treasure of special significance. There are also newer sections planted by humans.

Logging has long been allowed in the forest, but at a level considered sustainable. Poland's government decided last year to add logging in new areas, resulting in a threefold increase in the number of removed trees.

Environmental organizations reported the case to EU authorities, who have called on Poland to scale down the felling of trees. They say Warsaw is running out of time.

The head of Greenpeace in Poland, Robert Cyglicki, said Friday that the habitats of rare species like the Boros schneideri beetle are being destroyed by the logging and the use of heavy equipment.

Poland's Environment Ministry argues the intensified logging is done outside the oldest woodland and is intended to preserve the forest by preventing the spread of harmful bark beetle.

The ministry maintains the logging is in line with national and EU regulations.