By Theodora Arvanitidou

ATHENS (Reuters) - Hundreds of striking Greek sanitation workers ended a 10-day strike in Athens on Thursday over jobs as steaming mountains of garbage piled up across the country and temperatures soared.

Heaps of rotting rubbish have been steadily growing in Athens neighborhoods, raising fears of health risks as the country swelters in its first heatwave of the year. Garbage collection was expected to start later on Thursday.

"We decided to suspend the strike partly because of the heatwave, among other reasons," a union official told Reuters.

Union officials said they would explore other forms of labor action in the coming days.

With temperatures above 40 degrees (104 Fahrenheit) in some parts of the country, public sanitation workers who say their jobs are under threat marched through central Athens earlier on Thursday, many of them wearing their fluorescent work vests.

Some chanted "Tsipras your contract is up", a reference to Greek Prime Minister Alexis Tsipras, whose creditor-mandated austerity has seen him trailing in opinion polls.

"We want them (the government) to meet their promises. They promised to give us permanent jobs," said one worker, Marina Tsoukala, 57. "I'm close to pensionable age ... what private company would take us on?"

Garbage collectors fear job losses from new regulations governing short-term contract workers in the broader public sector, which includes local government. A court order banning extensions to short-term contracts could leave up to 10,000 jobs on the line.

Greek authorities had offered a compromise, giving existing contractors precedence over newcomers when the system changes.

Job security is a sensitive issue in Greece, where one in four is unemployed as the country wrestles with its seventh year of austerity sought by international creditors in return for bailouts.

With temperatures soaring, Athenians were for days advised to keep rubbish indoors to avoid it attracting rodents.

However, many neighborhoods were struggling with piles of trash overflowing from large wheelie bins.

"Its simply intolerable," said a woman who only identified herself as Vassiliki, 40. "I live on the fifth floor and the stench wafts up there. There are mosquitoes and flies, the smell is just awful."

(Additional reporting Lefteris Papadimas; Writing by Michele Kambas; Editing by Alison Williams)