* World's youngest nation torn by conflict since December
* Norway a major Western sponsor of South Sudan
* Oslo hosting donor conference on May 19-20
By Gwladys Fouche
OSLO, May 19 (Reuters) - Norway is pledging $63 million to help alleviate the humanitarian crisis in South Sudan, the Norwegian government said on Monday, amid expectations the conflict in the world's youngest nation to worsen in the months ahead.
The Nordic country, one of South Sudan's main Western sponsors together with the United States and Britain, is hosting an international conference to raise humanitarian funds for South Sudan on May 19-20 in Oslo.
Violence broke out last December, pitting President Salva Kiir's Dinka people against the Nuer of his former deputy, Riek Machar, whom the president sacked in July 2013.
"The crisis is expected to escalate significantly in the months ahead. The Norwegian Government is therefore allocating a further $63 million to humanitarian efforts in South Sudan," said Norwegian Foreign Minister Boerge Brende.
"By making this substantial contribution, Norway is sending a clear signal about the gravity of the situation," he said in a statement. The sum comes in addition to the $17 million Oslo has pledged in emergency aid to South Sudan this year.
The United Nations has now increased the funding requirement for humanitarian assistance from $1.3 billion to $1.8 billion. So far, donors have provided $590 million.
South Sudan became independent from Sudan in 2011. The fighting has curbed oil production, vital for its economy.
Norway said its money would be distributed via humanitarian actors on the ground in South Sudan, including United Nations agencies, the International Committee of the Red Cross and non-governmental organisations.
Some of the funds will also be allocated to relief efforts in South Sudan's neighbouring nations, which are hosting a large number of refugees, it said.
(Editing by Larry King)