Cybercriminals have targeted Auckland Transport's HOP system today, knocking out a number of services.

Online top-ups and transactions using Eftpos and credit cards were unavailable, but AT said customers could still catch buses, trains and ferries while the issue was being resolved.

Some ticket and top-up machines may also not be working.

AT said early indications pointed to a ransomware attack, but investigations were ongoing.

It is believed no personal or financial data had been compromised as part of the incident.

AT said it had spoken to all its public transport operators and asked them to ensure their staff are letting commuters onboard, even if they were unable to top up and use their AT HOP card.

It said cyber security was something it took extremely seriously, and it had activated its security protocols.

It was working to resolve the issue as quickly as possible, but AT anticipated it may take until early next week to fully restore services.

All affected services:

• Online top-ups, as well as other AT HOP services using MyAT HOP on their website, are currently unavailable.
• Existing auto top-ups will still work, but there will be a delay in the payment being processed.
• Ticket and top-up machines are only accepting cash payments. Transactions using Eftpos/credit cards are unavailable. Some machines may not be working.
• AT customer service centres will have limited functionality and may only be able to accept cash payments.
• AT HOP retailers are unable to top up HOP cards or process other AT HOP services like loading concessions.