Tanzania has asked energy firms conducting exploration for oil and natural gas in Lake Nyasa to halt their activities to allow international mediation to resolve the border dispute.
The 11,400-square-mile lake, also known as Lake Malawi, is one of Africa's Great Lakes, the third largest in Africa and eighth largest lake in the world. Lake Nyasa shares shores with Malawi, Mozambique and Tanzania and is also Africa's second deepest lake.
Lake Nyasa's largest tributary is the Ruhuhu River, which has a southern egress via the Shire River, a tributary that flows into the Zambezi River in Mozambique.
Malawi is contesting Tanzania's claim to half of the northern part of Lake Nyasa, maintaining that its borders on the shores of the Lake are regulated by the 1890 Anglo-German agreement.
Tanzania claims a 50 percent share of Lake Nyasa but Malawi claims the entire body of water.
In 2005 Malawi and Tanzania agreed to form a committee to negotiate the border and the lake's ownership but no definitive arrangements have been reached since then.
"We urge the Malawi government to respect our earlier agreement but we want Tanzanians to live in peace because we are going to protect our borders at any costs, Tanzanian Minister for Foreign Affairs and International Cooperation Bernard Membe said in a report in the Daily News newspaper in Tanzania.
"We urge the government of Malawi to refrain from any provocative actions that may worsen the situation. All options are possible but we like to give diplomacy a chance."
Membe added that the northeastern part of Lake Nyasa lies on latitude that makes it Tanzanian territory, which he maintains invalidates Malawi's claims.
Membe noted that the Tanzania Petroleum Development Corp. provided the government with information indicating that Malawi had leased out offshore Lake Nyasa concession blocs to international oil and natural gas prospecting firms, some of which fell on Tanzanian side of the lake.
Tanzania's Parliamentary Defense, Security and Foreign Affairs Committee is supporting the government's stance.
Committee Chairman Edward Lowassa said he expected the issue to be resolved diplomatically, using a mediator if necessary.
"Malawi is our neighbor and therefore we would not like to go into war with it," Lowassa said. "However, if it reaches the war stage then we are ready to sacrifice our people's blood and our military forces are committed in equipment and psychologically. Our army is among modern and stable defense forces in the world."
Malawi's Minister of Foreign Affairs and International Cooperation Ephraim Mganda Chiume sounded a more conciliatory note, telling reporters: "It is therefore very clear that Malawi and Tanzania have a different point of view on where the border should be. Government wishes to assure the nation that this should not be a cause for anxiety or alarm. ... The fact that our two countries are engaged in open and cordial discussions over the issue is a very good signal and therefore there should be no reason for any anxiety."