A landlord returned to his London flat weeks after it was vacated to find it covered in bird excrement, British media reported on Monday.

The birds had entered the two-bedroom flat after the previous tenants left the patio door ajar.

Over the course of the following four weeks, pigeons took over the flat and left their mark on every conceivable surface.

The living room and kitchen were worst hit.

One photo showed everything in the kitchen – from the drying rack to the toaster and floor – covered in bird poo.

British media quoted the landlord – who did not want to be named – as saying his eyes “popped out” when he entered the flat. He called a pest control company immediately.

Experts from the company said the flat was a “sight to behold”, with sofas, carpets and the TV similarly dotted with excrement.

Mr Paul Cooper, the managing director of London Network for Pest Solutions, said the pigeons had “redecorated” the flat and left it in a “complete mess”, according to a report in the Daily Mail.

He added that his firm’s pigeon expert had to put on a protective suit and two masks to block out the “overwhelming stench”.

The clean-up operation will reportedly cost £15,000 (S$26,000) and is expected to take about a month.