OTTAWA, May 18 (Reuters) - The Bank of Canada on Thursday said it was worried that a major cyber attack on one part of the financial system could quickly spread and threaten overall financial stability.

In an annual review of Canada's financial system, the central bank said a possible cyber attack had been a key threat since Russia invaded Ukraine in February 2022.

"A successful cyber attack in one part of the financial system could quickly spread to other parts and threaten overall financial stability," it said.

A severe incident could disrupt the delivery of services, cause major damage to compromised institutions "and weaken public confidence in the financial system", it added.

The bank said ransomware attacks on critical or widely-used third-party service providers remained a source of concern.

"This is particularly the case if the targeted supplier provides a critical service, such as telecommunications, to a large commercial bank or a prominent financial market infrastructure," it said.

Given the scale of the threat, financial system participants need to have rigorous response and recovery plans, it said.

(Reporting by David Ljunggren, editing by Steve Scherer)

Keywords: CANADA CENBANK/CYBER