Talks between Juba and Khartoum have collapsed as the former said it shot down a Sudanese war plane in Unity state today in South Sudan.

Speaking to Al Jazeera, Sudanese military spokesman Al Sawarmi Khaled Saad denied the accusations.

This comes a day after Sudan and South Sudan failed to reach an agreement on security at Tuesday's talks with Khartoum accusing Juba of continuing to support rebels in the country.

Khartoum alleged that Juba is supporting the Sudan People's Liberation Movement north in South Kordofan and Blue Nile.

The parties had agreed in principle that the African Union (AU) could monitor tensions on the border but no agreement on security was officially reached, they agreed to keep working to find a deal.

The head of the AU Thabo Mbeki also met with the two defence ministers, and each head of security separately to try to broker a deal but failed to do so.