Mugabe says some ruling party officials plotting against him

Zimbabwe President Robert Mugabe delivers his speech at the opening session of his party's 16th Annual Peoples Conference in Masvingo, about 300 kilometres, south of the capital Harare, Friday Dec. 16, 2016. Mugabe officially opened the conference where he is set to be endorsed as the ruling party candidate for Presidential elections set for 2018. (AP Photo/Tsvangirayi Mukwazhi) (The Associated Press)

Delegates wait for Zimbabwean President Robert Mugabe to officially open the session of the ZANU PF 16th Annual Peoples Conference in Masvingo, about 300 kilometres, south of the capital Harare, Friday Dec. 16, 2016. President Robert Mugabe officially opened the conference where he is set to be endorsed as the ruling party candidate for Presidential elections set for 2018. (AP Photo/Tsvangirayi Mukwazhi) (The Associated Press)

Zimbabwean first lady Grace Mugabe attends the opening session of the ZANU PF 16th Annual Peoples Conference in Masvingo, about 300 kilometres, south of the capital Harare, Friday Dec. 16, 2016. President Robert Mugabe officially opened the conference where he is set to be endorsed as the ruling party candidate for Presidential elections set for 2018. (AP Photo/Tsvangirayi Mukwazhi) (The Associated Press)

President Robert Mugabe of Zimbabwe says some ruling party officials have been plotting to oust him.

The 92-year-old Mugabe warned of threats to his long rule during a speech Friday at the opening of a ruling party conference in the southeast town of Masvingo.

The ZANU-PF party is expected to endorse Mugabe as its candidate for 2018 elections. He has been in power since independence from white minority rule in 1980.

Mugabe says some ruling party members have been punished for opposing his authority, and is warning others to stop using Twitter to criticize each other as a succession battle intensifies.

Opposition groups have organized periodic protests against Mugabe, saying he is too old and accusing him of mismanaging Zimbabwe's weak economy.