The amount of trash uncollected on Paris streets due to a waste workers strike has surged to 10,000 tonnes, despite efforts to force them back to duty, authorities said Friday.

The new estimate -- up from 7,600 tonnes earlier in the week -- comes after Interior Minister Gerald Darmanin said that strikers were being forced back under emergency powers designed to safeguard essential services.

"From today, from this morning, requisitioning is working and bins are being emptied," he told RTL radio.

An aide to Paris's Socialist mayor Anne Hidalgo, an opponent of Darmanin and President Emmanuel Macron, denied the change, saying that "no lorries have been out on the public side."

The city's municipal waste collectors began a strike and blockade of the city's incinerators 12 days ago over Macron's pensions reforms which will see them have to work until age 59, compared with 57 now.

They guarantee collections in around half of the capital's 20 districts, with the others handled by private companies.

Private companies were still working, with some of them taking contracts to clean up the increasingly smelly and crowded streets in the worst-affected areas.

Delphine Burkli, the mayor of the hard-hit 9th district, suggested Friday "calling in the army to clear the streets."