A terrifying video has surfaced from Russia of two swans attacking a swimmer.

In the clip, which was filmed a couple of years ago, a man plunges into the pond for a swim and is immediately set upon by the birds.

The swimmer is forced to duck under the water to avoid their pecks and tries to fend them off when he resurfaces.

Neither the simmer nor the swans were hurt in the attack.

According to ornithologists, swans can be very aggressive when defending a nest.