Senegal, one of West Africa’s largest economies, has torn up its tax treaty with Mauritius as debate rages over the island tax haven’s impact on developing economies.

Senegal unilaterally ended its double non-taxation treaty, or DTA, with Mauritius without fanfare earlier this year – and it is only now coming to the attention of tax officials in the region.

In the 2018 West Africa Leaks investigation, ICIJ revealed that a Canadian engineering giant avoided paying up to $8.9 million in taxes to Senegal with the help of a shell company in Mauritius.

ICIJ spoke to officials from Zambia, Lesotho, Uganda and the Republic of Congo who are seeking to modify treaties with Mauritius because the current deals are costing poorer countries millions of dollars in lost tax revenue each year.

One Senegalese official who wished to remain anonymous told ICIJ that it was important to cancel the treaty with Mauritius as soon as possible because recent oil and gas discoveries will bring an influx of investment to the West African nation.