HARARE, July 21 (Reuters) - South African President Thabo Mbeki arrived in Harare on Monday to oversee the signing of a deal that will pave the way for formal talks between Zimbabwe's ruling party and two factions of its opposition party.

Mbeki, who has mediated talks between the ruling ZANU-PF and the opposition Movement for Democratic Change, was met by President Robert Mugabe upon his arrival in the Zimbabwean capital, a Reuters correspondent at the scene said.