Sudan's oil ministry on Tuesday formally told oil companies to block the export flow of South Sudanese crude, following an order from President Omar al-Bashir.
Oil Minister Awad Ahmad al-Jaz presented the written directive in a meeting Tuesday with senior executives of the GNPOC joint operating company and Petrodar, the ministry said in a statement.
It orders them "to stop the process of transportation and exporting South Sudanese oil within 60 days starting from Sunday June 9", the ministry said.
On Sunday Khartoum froze nine security and economic pacts with South Sudan, including a deal to restore economically vital oil shipments through the Red Sea export terminal.
But the Khartoum government said it remained committed to good relations if the South's government in Juba ended support for rebels on Sudanese soil.