BERLIN - No suspicious substance was found in the consular section of the U.S. embassy in Berlin which was partly evacuated Thursday after employees felt unwell after touching suspicious documents, said a police spokesman.

A consular employee felt hard to breathe after receiving an envelope containing visa application papers from a man unknown, Michael Merkle said.

Two other employees also felt unwell after touching the same documents, he said.

Dozens of people in the building had been evacuated and the three had been sent to hospital, said Merkle.

But police found no suspicious substance in the building after investigation, said the spokesman.

For security concerns, the consulate remains partly closed and the three employees will stay in hospital for further treatment.

Merkle said identity of the man who brought the envelope in has not been confirmed yet and investigation is still under way.

The consular section of the U.S. embassy locates in Zehlendorf, a south-western district of Berlin.