A £90,000 repair programme at a Carmarthenshire school has been brought to a halt by a pair of nesting swifts.
The birds have made their home in the eaves at Burry Port Junior School forcing contractors to down tools.
As scaffolding was being erected last week the county council was informed by the Royal Society for the Protection of Birds (RSPB) that the swifts were present and that it was illegal to disturb them.
Part of the playground has now been fenced off and will remain out of bounds to the 200 pupils until the job can be completed.
A meeting is taking place on Thursday to discuss the situation but is possible the project may not be able to resume until July.
There is work needed ...unfortunately it has had to be delayed following advice that birds are nesting there
Carmarthenshire Council spokesman
It is estimated there are 80,000 pairs of swifts in the UK but their natural nesting habitats in holes in walls or under eaves are becoming fewer because of the modern design of buildings.
It was made illegal to disturb the nesting birds as part of the 1981 Wildlife and Countryside Act.
A spokesman for the RSPB said they were contacted by a member of the public as contractors arrived to start work.
"We then informed Carmarthenshire Council about the birds," he added.
Essential maintenance had already been completed at the school six weeks ago but there is substantial work needed to some of the walls of the building.
A spokesman for the council said: "There is work needed to be carried out at Burry Port School.
"The funding is now in place and we are ready to begin work.
Nesting swifts have stopped repair work
"Unfortunately it has had to be delayed following advice that birds are nesting there.
"Safety fencing has been put up and there is no danger to the children.
"A meeting is taking place on Thursday to discuss the situation."