By Nidal al-Mughrabi

GAZA (Reuters) - Authorities in Gaza have appealed for help to put out a fire that has been burning for days in a waste landfill site, sending foul-smelling smoke spiralling across the blockaded enclave which already suffers from severe environmental problems.

"We are working day and night, but unfortunately fires may go on for at least till the end of the week," said municipality spokesperson Hosni Mhana.

Boosted by a severe heatwave, the fire, southeast of Gaza City, close to the separation fence with Israel, has been burning in an area of roughly 50,000 square metres (539,000 sq. ft) of a landfill site which has swollen in the absence of recycling facilities.

"We have been unable to tolerate the smell of the fires for three days, it is not normal, you can't breathe," said Salem Abeid, 64, who lives around 1 km (0.6 mile) away from the landfill.

Citing security concerns, Israel and Egypt have enforced a blockade of Gaza since the Islamist Hamas movement seized control of the densely-populated coastal enclave in 2007, restricting the movement of people and goods.

Palestinians say these restrictions have severely impeded their ability to respond to emergencies.

Mhana said the lack of ways to recycle the garbage made the problem chronic, and the landfill only got bigger and bigger over the years.

"The environmental impact is huge because while some materials degrade, some other materials such as plastic do not and they stay in the soil," he said.

(Reporting by Nidal Almughrabi; Editing by Susan Fenton)