President Robert Mugabe has changed the constitution of his ruling ZANU-PF party to allow him to directly appoint his deputies, giving the 90-year-old sole power to anoint his successor, party sources said Sunday.

Until now Mugabe and his two ZANU-PF deputies have been elected by members from the country's 10 regions. The deputies automatically took up the same posts in government.

The changes to the ZANU-PF charter enacted at an all-night meeting of its politburo give Mugabe an even tighter grip at a time when Deputy President Joice Mujuru has been accused of plotting to oust him at a party congress next month.