Image copyright AP

Montreal has begun a controversial dump of 8bn litres (1.75bn gallons) of raw sewage into the St Lawrence River.

Officials in the Canadian city say that the project is necessary in order to replace old infrastructure in the sewage treatment system.

The operation has drawn the ire of people in Canada and in the US who have concerns that the river will be polluted with condoms and nappies.

The dump was delayed during the recent Canadian election.

Officials began releasing the raw sewage into the river just after midnight local time (05:00 GMT) on Wednesday, and say it could last about a week.

Media playback is unsupported on your device Media caption Sewage dumping kicking up a stink in Montreal

Citizens are being asked not to flush medication, condoms or tampons down the toilet while the operation goes on.

The diversion of the raw waste is needed so that workers can replace a snow chute - a large opening that funnels water from melting snow to a facility used to treat the sewage.

Officials at the city of Montreal have said the dump will have little effect on the fish population and will not affect the quality of drinking water for citizens.

Image copyright Reuters Image caption A sign reading "Don't touch the water" can be seen near the river

The plan was approved by Canada's new environment minister on the condition that a host of conditions including extensive monitoring were abided by.

However, the plan has drawn ire on both sides of the US-Canada border.

Mathieu Traversy, a provincial legislator of Parti Quebecois, said cities were concerned that riverbanks would be marred by "diapers, condoms and syringes".

Across the border, Senator Chuck Schumer of New York has asked the US Environmental Protection Agency (EPA) to intervene.

For its part, the EPA has said it has no regulatory authority over the river, which lies entirely in sovereign Canadian territory.