Zimbabwean President Emmerson Mnangagwa. File photo: ANA

Harare - Zimbabwe police said Tuesday they had arrested two suspects over the grenade blast at an election rally that killed two people and narrowly missed President Emmerson Mnangagwa.

Police chief Godwin Matanga said investigations were continuing over the explosion in the country's second largest city of Bulawayo on June 23.

"I would like to applaud the level of cooperation and support that the joint investigation team has so far received, culminating in two suspects being accounted for," Matanga said while addressing police officers in Bulawayo.

"We will never rest until all those behind this heinous act have been accounted for and have their day in court."

Matanga declined to take questions from journalists or give further details.

Last week two suspects who were in police custody on alleged terrorism and banditry charges failed to appear in court and were reportedly later released without charge.

Police and security agencies have released few details about the investigation.

Mnangagwa, who took power from veteran leader Robert Mugabe after a brief military takeover, has accused aggrieved supporters of Mugabe's wife Grace of being behind the attack.  

About 50 people were injured in the blast, which exploded as Mnangagwa left the podium after addressing supporters of the ruling ZANU-PF party.

Mnangagwa is facing off against main opposition leader Nelson Chamisa, 40, from the Movement for Democratic Change (MDC) party, in a presidential race that has 23 candidates.

Previous elections under Mugabe were marred by violence, intimidation and fraud.