President Robert Mugabe of Zimbabwe sharply criticized his vice president, underscoring that she is no longer a favorite to succeed the 90-year-old leader.

Mugabe told military leaders and representatives of Zimbabwe's independence war veterans on Tuesday that Vice President Joice Mujuru was working with the political opposition as well as the United States. Washington has criticized Mugabe's human rights record and imposed some sanctions on officials and entities in the southern African country.

Mugabe's address was broadcast on state television and came during a key ruling party congress at which the president is poised to consolidate his grip on power by appointing a new set of loyalists, including his wife Grace.

Mugabe said Mujuru "didn't want" 2013 elections that he won. The opposition alleged the vote was marred by irregularities. Power struggles involving the vice president are rocking the ruling ZANU-PF party for the first time, he said.

"It is a woman who is saying she now wants to rule. We know the infiltration that has gone on. We know the discussions that have been done to link up with the (political opposition) and America will then pour in money," Mugabe said. "You know that simplistic thinking."

Mujuru, a member of Mugabe's inner circle since the 1970s independence war, has already been barred from running for a seat in a key party committee.

The state-run Sunday Mail newspaper has alleged that Mujuru was involved in an assassination plot against Mugabe, who has been in power since independence in 1980. Mujuru has denied the allegations, saying she was prepared to defend herself in court.