Uganda’s government accused neighboring Rwanda of imposing an embargo on bilateral trade, the latest salvo in an escalating dispute between the two countries.

Rwandan authorities blocked Ugandan exports to the country and introduced an export-permit system for Rwandan traders seeking to ship goods to Uganda, the Foreign Ministry said in a statement posted on government spokesman Ofwono Opondo’s Twitter feed.

The “export of Ugandan goods to Rwanda have been prohibited by Rwanda authorities,” the ministry said, describing the export-permit system as a “technical non-tariff barrier” to trade. “In effect, this is a trade embargo on bilateral trade with Uganda.”

The two East African nations have been at odds since last month, when Uganda accused Rwanda of blocking their citizens from crossing a border crucial to trade.

Rwandan Trade Minister Soraya Hakuziyaremye cut calls to her mobile phone seeking comment.