Canada has made an offer to the Philippines to repatriate six dozen shipping containers full of rotting garbage that were erroneously shipped there six years ago, the federal environment minister said today.

"This is a file we've certainly been working hard on for a long time — obviously an irritant in our relationship with the Philippines, but also a problem," Catherine McKenna told reporters in Ottawa Thursday.

"We've had a team that's been working extremely hard, including from Environment and Climate Change Canada, to find a solution. I am not going to go into the details but there is a proposal on the table with the Philippines and we are hopeful we can come to a resolution."

McKenna said she would not "speculate" on where the garbage will go when it returns to Canada, nor would she disclose the cost of bringing the trash home.

According to Adam Austen, a spokesperson for Foreign Affairs Minister Chrystia Freeland, the Philippines has yet to respond to Canada's offer.

If the offer is accepted, the trash would return to Canada through the port of Vancouver before disposal.

The international dispute has been brewing since 2013 and 2014, when a Canadian company shipped about 103 containers wrongly labelled as plastics for recycling to a port near the capital Manila.

The Canadian offer came around the same time as the Philippines ordered its Bureau of Customs to get the containers back on a ship bound for Canada no later than May 15.

Last month, President Rodrigo Duterte threatened to "declare war" on Canada if it didn't take back its trash and set this week as a deadline for an end to the impasse.

"I will declare war against them," he said at the time in a video broadcast by RTVM, the media arm of the president's office. "I will advise Canada that your garbage is on the way. Prepare a grand reception. Eat it if you want to ... your garbage is coming home."

Officials check a shipping container holding Vancouver garbage in Manila in this undated photo. About 100 incorrectly labelled containers full of garbage were sent to the Philippines from Canada about six years ago. (Philippines Bureau of Customs)

Duterte's colourful comments were matched by his foreign secretary Teodoro Locsin, who tweeted this week that he is going after the Filipino importers who brought the trash into the country but dismissed suggestions they should be sent to Canada with the garbage because that would be "too much pollution."

Canada is a party to the UN Basel Convention, which is meant to reduce transfers of hazardous waste to developing nations without their consent.

In 2016, Canada strengthened its regulations around hazardous waste shipments to include the obligation to take back waste shipments that cannot be completed as planned.