* Mineworkers union to decide on shutdown April 28
* Number of dead miners in 2011 is 50 - Union
By Ruona Agbroko
(Recasts with clarification on dates, new quotes)
JOHANNESBURG, April 15 (Reuters) - South Africa's powerful National Union of Mineworkers (NUM) will decide on April 28 when to shut the sector down for a day to protest a rise in mining deaths, it said on Friday.
The NUM said in a statement on its website its national office bearers would recommend next week "that a National Day of Mourning be observed where no single mining operation will operate in the country."
But its spokesman told Reuters the union would only meet and make an announcement in the last week of April.
"The national executive committee will sit on the week of the 28th of April. The national day of mourning will be announced on that week," spokesman Lesiba Seshoka said.
South Africa is the world's top platinum producer and a major gold producer.
The Department of Mineral Resources says mineworker deaths have risen over 25 percent in the first quarter of this year to 38, compared to the same period last year.
But Business Day newspaper on Friday said NUM alleged the death toll was in fact closer to 50.
The union explained that it based its figures on deaths to include the first two weeks of April
"The number of mine deaths has increased to 50, because the figure of 38 that is bandied about by the Mineral Resources department is until the end of March. Fifty is the current figure until yesterday," Seshoka said.
In some of the recent incidents, a worker was killed in a locomotive accident on Thursday at Harmony Gold's Masimong mine and last week two were killed at Gold Fields' KDC mine.
NUM represents about 340,000 workers in the mining, construction and electrical energy industries of Africa's largest economy.
Labour relations in South Africa's key mining sector are fraught and mine safety is a massive issue, especially as the gold companies have to take their operations deeper and deeper. (Editing by Ed Stoddard)