Nearly half a million more voters were found to have duplicate records and more than 226,000 people were registered using documents that do not belong to them.

Others had registered with invalid documents, the Independent Electoral and Boundaries Commission (IEBC) said in a statement on the anomalies that affect more than a million people.

IEBC chairman Wafula Chebukati said that because of the “implementation of the preliminary audit findings” the commission would delay certifying the final register for publication.

The commission said earlier that it would publish the register of voters on or before 9 June but has pushed that to 20 June as it seeks to address the findings by KPMG, the firm contracted to do the audit.

Electoral irregularities in past elections in Kenya have led to deadly violence. This year's elections will be held on 9 August.

Four presidential candidates have been cleared to run in the election - David Mwaure, George Wajackoyah, Raila Odinga and William Ruto.