Tanzania's ruling Chama Cha Mapinduzi party has picked the energy minister as its nominee for the new vice president, the party's secretary general said late on Wednesday, after the incumbent announced his resignation less than a year into the job.

Outgoing Vice President Emmanuel John Nchimbi will leave office on September 4, having served since last November. His resignation followed criticism from some in the party for remarks about the constitution last month that they considered unnecessary.

The ruling party's National Executive Committee has now picked Deogratius Ndejembi for nomination as the next vice president, ruling party secretary general Asha-Rose Migiro told reporters.

NEC "has unanimously approved that member to take the position of Vice President. This will take place after completing the constitutional procedures that require his name to be submitted to Parliament," Migiro said.

Ndejembi would be sworn in after he has been approved by parliament, she added.

She said the ruling party had also decided to expel Nchimbi from the party "due to conduct that violated our regulations regarding discipline and ethics". She did not say what conduct violated the party's rules.

Last month Nchimbi urged Tanzanians to fight for a new constitution, "a constitution that leads us toward development, not just material and economic development, but the development of dignity and the human worth of every person living in Tanzania," he said.

President Samia Suluhu Hassan won last year's presidential election with nearly 98% of the vote, in an election marred by deadly violence.