About 170,000 workers in Syria lost their jobs because of the earthquake that struck the region last month, leaving about 154,000 households and more than 725,000 people directly affected, a report said.
At least $5.68 million is being lost every month in the country as a result, a report by the International Labour Organisation said on Wednesday.
It said in the 11 affected provinces in Turkey, the hours of work lost were the equivalent to work done by around 657,000 people.
The 7.8-magnitude quake that struck on February 6, and its aftershocks killed more than 55,000 people across south-eastern Turkey and parts of war-torn Syria.
"People can only begin to rebuild their lives if they have rebuilt their livelihoods," said ILO chief Gilbert Houngbo.
"We owe it to those who have lost so much in the earthquake to ensure that the principles of social justice and decent work are firmly embedded in the recovery and reconstruction process."
The ILO calculated that the average affected worker in Turkey would lose around $230 a month "as long as the situation continues".
Overall, the crisis is estimated to reduce the take-home labour income of the affected region by around $150 million per month.
Besides job losses, the ILO warned of increased risks to occupational safety and health in Turkey, as well as child labour.
Around 35,000 micro, small and medium-sized enterprises have been affected.
"The loss of these businesses goes beyond the loss in incomes and encompasses the cost of the physical damage to their infrastructure, such as buildings, equipment, and inventory," the ILO said.
In Turkey, the ILO said it was helping Turkish business organisations and trade unions to function and provide critical services, with initiatives on seasonal agricultural workers, child workers and refugees.
In Syria, the UN agency is providing grants to help support affected workers and businesses.
“The earthquakes have had a devastating impact on livelihoods and the local economy in Syria, compounding the already dire economic and labour market situation caused by 12 years of war and conflict,” said Tariq Haq, the ILO's senior employment policy specialist for the Arab states.
“These losses have an impact not only on the lives of the unemployed workers themselves, but also on the lives of those who depend on them.
"The new ILO assessment aims to understand the current situation and identify areas of need that require immediate action in order to support quick and inclusive recovery in line with the principles of decent work and social justice.”