The U. S. ambassador to South Africa accused the country Thursday of providing weapons and ammunition to Russia for its war in Ukraine via a cargo ship that docked secretly at a naval base near the city of Cape Town for three days in December.

Questions were raised in South Africa’s parliament on Thursday and President Cyril Ramaphosa said an investigation was underway.

Ambassador Reuben Brigety said the U.S. was certain the equipment was loaded onto the Russian vessel at the Simon’s Town naval base and then transported to Russia, according to reports of his comments carried by multiple South African news outlets.

Ramaphosa was in Cape Town answering questions in Parliament when news of Brigety’s comments broke.

When a lawmaker asked about the weapons and ammunition, the president replied that “the matter is being looked into, and in time we will be able to speak about it.”