MAPUTO (Xinhua) -- Joaquim Chissano, former Mozambican President, has been asked to mediate in the border dispute between Malawi and Tanzania, over Lake Niassa.

According to the Mozambique News Agency (AIM) on Monday, Malawian Foreign Minister Ephraim Chiume said that representatives of the two countries will deliver the formal invitation to Chissano in Maputo on Thursday.

The invitation should have been delivered two weeks ago, but Chiume said that had not been possible because the Tanzanian side had not concluded its part on time.

The foreign minister said Chissano will head a team of former heads of state of the Southern African Development Community (SADC) to mediate the dispute on how the northern part of Lake Niassa should be divided between Tanzania and Malawi.

The two countries tried to resolve the problem, but failed to do so for many rounds that started in August this year.

They had decided to call for assistance from former southern African presidents. Should this mediation fail, Chiume was quoted by AIM as saying that the matter will be remitted to the International Court of Justice.

Malawi is claiming all of the northern part of the lake, based on the Heligoland Treaty of 1890 between Britain and Germany, at the time Malawi was under British rule, and Tanganyika was a German colony.

Tanzania, however, wants a dividing line drawn through the middle of the lake, which is how boundaries between countries who share lakes are normally dealt with.

The Lilongwe administration hopes the matter can be resolved by the end of 2013. It has become urgent due to the reserves of oil and natural gas that are believed to lie under the lake.

Malawi’s decision to give exploration rights in the whole lake to a British company, Surestream, has led to the current situation.

Tanzania has said that it was ready to shade blood if its side of the lake is usurped by Malawi.