The blast left a “dent” on the perimeter wall around the MDC-T secretary general’s home in Highlands, the party added in a statement.

The statement did not say if Biti was home at the time.

“Neighbours said the incident happened an hour after midnight when they heard the blast, but were too afraid to come out,” the statement said.

Gift Kaseketa, reported to have been inside the house at the time, said he “did not see anyone, and neither did he hear any sound of a vehicle”.

“He was only able to see the dent left by the detonator in the morning. Only marks of the futile attempt are visible to the wall,” the party added.

Calling for a “thorough investigation”, the MDC-T said it “does not take this attack lightly given that there have been increasing criticisms and verbal attacks on Hon Biti lately.”

The party referenced a story in the privately-owned Standard newspaper on Sunday claiming President Robert Mugabe and military chiefs had given Biti an ultimatum to award civil servants pay rises.

Nelson Chamisa, the party's organising secretary added: "Hon Biti blocked the paths they used to siphon funds from the government for personal use, so they are feeling the pinch, and are furious at him and the MDC."