Medics attend to people injured in an explosion during a rally by Zimbabwean President Emmerson Mnangagwa in Bulawayo, Zimbabwe. Picture: Tafadzwa Ufumeli/via Reuters

Harare - Two people died on Monday from injuries they suffered when an explosion rocked an election campaign rally by Zimbabwean President Emmerson Mnangagwa at the weekend, a state-owned newspaper reported.

Mnangagwa escaped unhurt from the blast on Saturday in the city of Bulawayo, an opposition stronghold, and police have said they were searching for a motive.

Police originally said 49 people had been injured at the rally, the first in Bulawayo by 75-year-old Mnangagwa in his campaign for presidential and parliamentary elections on July 30.

The vote is being held after Robert Mugabe was forced to resign as president following a de facto coup in November. Mugabe has said he felt betrayed by Mnangagwa, a former protege, and has called his presidency illegal.

Quoting officials at Bulawayo's Mpilo Hospital, the Herald newspaper said on its website that two people admitted to the institution had died from their injuries.

A ruling Zanu-PF party official said earlier that one of the victims was a member of the Presidential Guard, an army unit that provides close security to Mnangagwa and his two deputies.

Mnangagwa has said the blast would not stop the election, which is being monitored by foreign observers for the first time since 2002. The European Union deployed its long term observers around Zimbabwe on Saturday.

National police spokeswoman Charity Charamba said she would issue a statement later while Health Minister David Parirenyatwa, who has been monitoring victims in Bulawayo hospitals, did not respond to calls for further comment.