Niger's Prime Minister Ali Mahaman Lamine Zeine said on Saturday that Benin's blockade of its oil exports violated trade agreements between the two countries and with Niamey's Chinese partners.

    In a comment that further escalated the dispute, Zeine said Niger could not fully reopen its border with Benin for security reasons.

    In response, Cotonou said it would only back down once Niamey reopened its border to goods coming from Benin and normalised relations.

    The blockade jeopardises Niger's plan to start exporting crude oil to China under a $400 million deal.

    A 2,000 kilometre-long Chinese-built pipeline links Niger’s Agadem oil field to Benin’s port in the capital.

    Relations have been strained between Niamey and Cotonou since a military coup in Niger last year.

    It led Benin and the West African regional bloc (ECOWAS) to impose strict sanctions on Niger, including border closures, in a bid to force the military to hand power back to the elected government.

    These were eased in February, but Niger has refused to reopen is land border to goods coming from Benin.