The rights group said it would try to recover lost funds, while assuring donor money was safe.
An “extensive forensic audit was conducted in late 2018 which uncovered evidence of fraud and serious financial mismanagement,” Amnesty said in a statement on Thursday.
It said that the Zimbabwe branch had been suspended from the global organisation and placed under administration and that the Zimbabwean police had been informed of the audit findings.
“The decision has been made to take extraordinary measures … to protect the reputation, integrity and operation of the movement,” it added.
The London-based rights group gave no further details and said it would not provide spokespeople for interviews, but said it would try to recover lost funds and that urgent measures had been introduced to ensure donor money was safe.
Amnesty has focused recent work in Zimbabwe on campaigning against the arrest of rights activists, promoting media freedom and calling for accountability for security forces after alleged abuses.
Last year, the United States cut funding to three Zimbabwean civil action groups citing “possible misuse” of money.
International rights groups in Zimbabwe have often been accused by state media of working on behalf of foreign countries to help the main opposition Movement for Democratic Change (MDC) party to overthrow the government.
Thursday’s suspension comes two days after Amnesty lost most of its senior leadership team following an independent review into what employees called a “toxic” workplace.
All seven members of the senior leadership offered to resign on Tuesday and five are believed to have left or been in the process of leaving the organisation.
The review was ordered by Amnesty’s Secretary-General Kumi Naidoo after two employees killed themselves last year.