Turkish police on Saturday arrested at least 20 people, including an AFP photographer, as they broke up a protest against work-related deaths and poor conditions at the construction site of Istanbul's third airport, touted to be the world's largest airport when completed.

The security forces moved in to break up the protest by dozens of people following a wave of arrests on Friday.

Among those held by police on Saturday was AFP photographer Bulent Kilic who was covering the event.

In total some 500 people have been arrested during protests at the site of what is one of President Recep Tayyip Erdogan's mega development projects, according to Turkey's Revolutionary Unions Confederation (DISK).

Security forces had on Friday dispersed a demonstration by hundreds of workers outside the new airport, which was due to be completed in October, the private DHA news agency reported.

The protesters complained of work-related deaths and accidents as well as poor on-site living and labour conditions.

The opposition daily Cumhuriyet quoted live-in workers complaining about fleas and bed bugs.

The airport construction and operating company, Istanbul Grand Airport, issued a statement saying management had met the workers and pledged to take measures to resolve the issues quickly.

A spokesman for IGA refused further comment on Saturday.

The hashtag supporting the workers, “we are not slaves” (#kledegiliz) was trending strongly in Turkey on Saturday.

Dozens of security forces, backed by armoured vehicles, controlled access to the site on Saturday, AFP journalists said.

When the first plane landed at IGA in June, Erdogan said the new airport will be the biggest in the world with a first phase capacity of 90 million passengers a year going up to 150 million in 2023.

Some 35,000 people are employed on the project including, 3,000 engineers and administrative staff.

Twenty-seven workers have died at the construction site —13 in work-related accidents, the transport minister said during a press visit to the airport last April.

However, several workers, asking not to be named, told AFP on Saturday that the ministry figures were far too low and that accidents were very common at the site.