Police in Germany are investigating whether a box of sandwiches contained a poisonous substance after 20 people who ate them were admitted to hospital as a precaution.

The suspicious sandwiches were left on the doorstep of a company in the north-western town of Vechta with a note saying they were a gift.

Police said 25 employees ate the sandwiches before someone noticed a strange substance on them.

Police spokesman Klaus Koesterke said today that so far none of those taken to hospital has shown symptoms of poisoning.

But authorities are not excluding the possibility of a slow-acting poison and have rushed samples of the sandwiches to a Berlin laboratory for tests.

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