Somalia has turned away a plane transporting officials from Ethiopia to the self-declared republic of Somaliland in a major escalation of the diplomatic row between the countries.

Somalia's information minister told the BBC the plane did not have permission to be in the country's airspace.

The Ethiopian officials were visiting Somaliland to discuss a deal, which has sparked a huge row.

Somalia considers Somaliland to be part of its territory.

The agreement, signed on 1 January, would allow Somaliland to lease one of its ports to Ethiopia in exchange for a stake in Ethiopian Airlines and possible recognition of Somaliland as a sovereign state.

Somalia has reacted angrily to the deal, calling it an act of aggression.

On Wednesday, the Somali Civil Aviation Authority (SCAA) said flight ET8273 had broken international rules that flights must obtain clearance from countries they are passing through.

It had attempted to land at Somaliland's Hargeisa Airport.

Despite this incident, regular flights between the two countries are operating as usual, the SCAA said.

Ethiopia's government has not yet commented, but the head of Ethiopian Airlines confirmed that the plane in question had returned to the nation's capital, Addis Ababa.

Somaliland, a former British protectorate which declared independence from Somalia in 1991, has all the trappings of a country, including regular elections, a police force and its own currency.

But this has not been recognised by any country.

By ordering the Ethiopian plane out of its airspace, Somalia is sending a strong message that Somaliland is not an independent country.

Amid the row between Somalia and Ethiopia, both the US and the African Union have backed the territorial integrity of Somalia and urged all parties to cool tensions.