A firm was fined £500 and ordered to pay £1,882 costs for putting up scaffolding without permission.

Fergal Contracting Co, of Standlake, near Witney, pleaded guilty at Oxford Magistrates' court.

The scaffolding was put up in the Rewley Abbey stream, near Oxford railway station, so that workers could paint a bridge.

The prosecution was brought by the Environment Agency which said the company had failed to wait for consent to put up the structure, and ignored advice not to do so.

Agency officials said the scaffolding stopped boat users travelling along the waterway safely because it forced them to a shallow part of the stream.

The Rewley Abbey Stream, known as the Sheepwash Channel, connects the River Thames to the Oxford Canal.

An agency spokesman said they had received an application from Fergal Contracting on July 27 to carry out the work. It sent a reply advising that work could not start until consent had been given.

But scaffolding was built in the stream, where it was seen by an agency officer on August 7.

The agency then sent a fax to Fergal, outlining the navigation safety requirements it had to keep to. It also warned the company that if it put the structure in the navigation channel, it might be liable to prosecution.

Tom McCormack, agency flood defence officer, said prosecutions were rare but the case highlighted the need for consent before work of this kind began.