Google and Apple Inc’s “symbiotic relationship” should get scrutiny from the UK’s antitrust regulator, a group of online advertisers said.

Marketers for an Open Web said it has asked the Competition and Markets Authority to look at concerns that the two companies “are not competing head to head”, citing US regulatory filings on agreements between the tech giants that they say are a form of active collaboration.

The UK regulator is one of several global antitrust enforcers examining technology companies amid concerns they may have too much power. The CMA started an investigation earlier this month into Apple’s app payment rules following scrutiny of Google’s planned advertising changes. The Google probe was sparked by a complaint last year from the Open Web group.

The US Department of Justice’s lawsuit last year alleges that Google and Apple work as “one company” on search. It alleges that Google’s exclusive paid deals to distribute its search engine on browsers and phones, including Apple’s iPhones, violate monopoly rules. It’s the most significant US monopoly case in more than 20 years. Texas is also leading an antitrust lawsuit into digital advertising.

Google referred to earlier blog posts on the US legal action that said its agreements with Apple and others mimic other software distribution deals and have withstood repeated antitrust reviews. The deals don’t prevent consumers from switching to other search providers. The company argues its success rests on superior technology.

The CMA declined to comment. Apple didn’t immediately respond to a request for comment.

Marketers for an Open Web is asking the CMA to request internal documents from the companies on meetings and communications such as those cited in the US lawsuits, according to the group’s lawyer, Tim Cowen. The group made a filing last week to ask the CMA to investigate Apple’s ads and web tracking, an issue France is also examining even as it rejected advertisers’ requests to halt Apple’s ad changes.

Google and Apple are both rolling out privacy changes to curb how users are tracked on their devices. Advertisers and publishers complain that the companies’ actions to limit access to data will hurt their ability to generate ad revenue and undermine their business models.

 - Bloomberg