The UK’s data watchdog is investigating a surge in complaints about spam “robo calls” where a recorded voice asks you to add them on WhatsApp.

The Information Commissioner’s Office (ICO) said the number of complaints about automated nuisance calls had almost tripled in just three months, reaching its highest level since 2021.

Complaints from the general public to the data protection regulator rose from 1,374 in July to 2,178 in August, an increase of 58 per cent, before climbing a further 69 per cent to 3,684 in September.

Experts warn these calls could lead to a recruitment scam, as the automated calls typically come from a UK mobile number, with some offering part-time work or tricking people into joining WhatsApp groups.

Andy Curry, the ICO's head of criminal investigations, said he believed the reported figures were just a small proportion of the issue.

"The sharp rise in complaints about automated calls is deeply concerning. These calls are not just a nuisance; they can cause real distress and are often designed to manipulate people into handing over personal information or money,” he said.

"The numbers we're seeing are likely to be just the tip of the iceberg. We know many people simply hang up and move on without reporting what happened.”

He called on people to report any suspicious automated calls to the ICO so they can take enforcement action.

"Our message is simple: if you receive a suspicious automated call, report it to us by using our simple online form,” he added. “Every report helps us build a clearer picture of who's behind these calls and strengthens our ability to take enforcement action.

“The more information we have, the better equipped we are to identify patterns, investigate those responsible and protect the public from harm. Your complaint could play a vital role in helping us stop these operations."

Simon Fell, from the Communications Crime Strategy Group, a telecoms industry body set up to tackle fraud, told BBC Radio 4’s You and Yours show that these calls appear to be trying to put call recipients through to a fake job listing which could put people at risk of fraud.

"They would either put you through to a fake job listing, which might involve some form of money muling. It could look like a completely legitimate job, or something ad hoc, but they might pass criminal funds through your account which can lead to terrible consequences,” he said.

"It could also be a simple phishing exercise – criminals send out these messages, and what they really want to know is who's picking up, who's active – that information can be resold on the dark web.

"The possibilities are endless. At the end of the day, this is a criminal that has reached out to you, and they're trying to defraud you in some way, shape or form."

Kevin Walker, founder of Black Swan Cyber Security Solutions, said the biggest warning sign for these scams is an unexpected caller trying to move call recipients onto another platform before explaining who they are or why they’re calling.

“A genuine recruiter should be able to identify their company, explain the role and provide details you can independently verify,” he told .

“Be wary of vague job offers, promises of easy money, requests for payments, verification codes, identity documents or links to unfamiliar websites.

“Don't assume somebody is genuine just because they know your name, employer or that you're looking for work. That information can be obtained from public sources and previous breaches.”

He added that in the UK, suspicious mobile calls can be reported through 7726.

“If you've already replied, don't panic. A conversation doesn't automatically mean you've been compromised. But if you've shared passwords, verification codes, banking details or money, act quickly.

“These scams exploit normal human behaviour. Curiosity, politeness and an interest in a job opportunity aren't character flaws.

“I've never liked describing people as the weakest link in cyber security. Criminals deliberately create situations where perfectly ordinary decisions can have serious consequences. We shouldn't need everyone to become a fraud expert just to answer their phone.”

The ICO warned people not to answer numbers they don’t recognise and to report any nuisance calls.

People can also register their number with the telephone preference service (TPS) free of charge, which is a register of people who have said they don’t want to receive marketing calls.

WhatsApp has in-built features to protect users from scam calls, such as automatically silencing calls from unknown numbers.

The platform also show user context cards, which tell them when a new contact is getting in touch and whether they have groups in common, as well as the country they’re messaging from, so users can decide whether to respond or report.

All images sent by unknown contacts are blurred by default, and you can block or report a contact to WhatsApp at any time.

The platform also disables links from unknown senders until users choose to engage with them as scammers often try to pressure people into sending money or clicking on malicious links.

A Meta spokesperson added: “Beyond that, we have systems in place to detect malicious behaviors like bulk account registration, automated messaging, or creation of large numbers of groups. Together, these systems ban millions of accounts every year, often at registration or before anyone reports them.”