Seagull numbers in Cardiff have more than doubled in the past five years, a report says.

Gull expert Peter Rock examined the Severn Estuary, also covering Swansea, Gloucester, Bristol and Swindon.

The draft study looked at 38 different seagull colonies across the Severn Estuary region of south Wales and the west of England.

His research found that the Cardiff's 6,000 seagull population is the largest in the region and is causing problems for residents as well as businesses.

James Byrne of RSPB Cymru said the Welsh capital had become an ideal place for the birds in recent years.

"There's a lot of food and nesting places for them in Cardiff, and that creates a pull factor," he said.

"There's also a push factor in that in the rest of the UK seagulls are declining massively."

Cardiff Council's pest control department said the increase in numbers was a tricky problem to tackle.

Clive Bryant, from the department, said: "Some buildings, even commercial ones, have no access to the roof which gives these birds a free reign up there.

"They can get really aggressive in the summer when they're laying their eggs."

The RSPB, the report's author and Cardiff Council all said they welcomed any further research into why the bird population had increased.

Seagulls have also been identified as a problem in other areas of Wales.

In Rhyl, The White Rose shopping centre installed wires above its car park to deter more than 1,000 seagulls earlier this year.

Its owners claimed it was losing customers and called in pest control experts to tackle the problem of droppings created by the roosting gulls.

And last year, Aberystwyth University installed speakers mimicking the sound of distressed seagulls to prevent hungry gulls from bothering diners near a cafe.