JOHANNESBURG - Former South African president Jacob Zuma's uMkhonto we Sizwe (MK) party has filed an application in the constitutional court to try to block the first sitting of the National Assembly since last month's election, it said on Tuesday.

South Africa's newly elected parliament is due to convene on Friday for the swearing-in of lawmakers and the elections of its speaker and deputy speaker as well as the country's president.

Zuma's MK party came a surprisingly strong third in the May 29 vote but has alleged vote-rigging took place and threatened to boycott the new parliament.

The Independent Electoral Commission and other parties said the election was free and fair, and South Africa does not have a history of significant vote fraud.

The election saw the African National Congress (ANC), Zuma's longtime political home, lose its parliamentary majority for the first time since it came to power at the end of apartheid 30 years ago.

The ANC is now negotiating with potential partners ranging from Marxists to free-marketeers about setting up a national unity government.

(Reporting by Tannur Anders and Alexander Winning Editing by Estelle Shirbon)