OTTAWA -- Canada has agreed to pay the full cost of bringing 69 garbage-laden shipping containers back across the Pacific Ocean to Vancouver -- but it remains unclear how much it will cost and when it will happen.

The Canadian government made a formal offer to bring back the garbage last month but has remained tightlipped about what the offer contained.

The Philippines has been far more open with information ever since President Rodrigo Duterte threatened to "declare war" on Canada if the garbage was not taken back. He has given Canada until May 15 to get the containers out of the two Philippine ports where they have been sitting for nearly six years.

In a written statement Tuesday, the Philippine Department of Finance said Canada offered in writing on April 24 to arrange for and cover the full cost of shipping the 69 containers that remain from the original 103. A Global Affairs Canada spokesman, who spoke on the condition of anonymity to discuss matters Canada hasn't yet made public, confirmed the offer included costs, but wouldn't give any other details.

Environment and Climate Change Canada is in charge of hiring a firm to bring the trash back and then disposing of it in Canada. Caroline Theriault, deputy director of communications for Environment Minister Catherine McKenna, said all the details are still being worked out with the Philippines.

The containers arrived in the Philippines in 2013 and 2014 labelled as plastics for recycling, but were found to mostly contain trash, triggering a long back-and-forth between the two governments over which of them should deal with the problem. There were originally 103 containers but the contents of 34 have already been dealt with in the Philippines.

Canada's formal offer to pay to bring them back came the same day Duterte made his threat of war, which another government official later clarified was not a true threat but rather made to underscore how unhappy Duterte was that the garbage was still in his country.

Philippine Customs Commissioner Rey Leonardo Guerrero said Tuesday all the export permits needed from the Philippines are in place but that Canada's import permits are not.

"However, despite the Philippine government's readiness to re-export the wastes, the Canadian government informed that it might take weeks for them to arrange the necessary documents from their end and that they might not meet the May 15 deadline," Guerrero said in a statement.

Teddy Locsin, the Philippine foreign secretary, said on Twitter Tuesday he didn't care about Canada's paperwork.

"The President expects the garbage to be seaborne by May 15," he wrote. "That expectation will be met or elseΓÇª"

He did not specify what "or else" meant.

The Philippine department of finance said the two countries agreed on May 3 that the Philippines will pay for the cost of inspecting the containers to make sure they are seaworthy, and Canada is to cover the costs of fumigating and transport. Over the last several days, the shipping lines involved reported that all 69 containers are safe to transport except for one that has become infested with termites. That container can be shipped as long as it is secured on a flat rack container.