The United Kingdom’s mobile browser market is “not working well for consumers and businesses” according to a final report from Britain’s competition watchdog, which says that Apple and Google are largely to blame.

An independent inquiry group has concluded its mobile browsers investigation for the Competition and Markets Authority (CMA), identifying Apple’s policies around iOS, Safari, and WebKit as making it difficult for third-party web browser providers to compete and restricting the market as a result. Google’s Android mobile ecosystem is also complicit in impeding competition, according to the CMA report, albeit to a lesser extent.

The issues flagged by the investigation include Apple requiring all browsers on iOS to run on its WebKit browser engine, giving Safari preferential access to features compared to competing WebKit-based browsers, limitations placed on in-app browsing, and having Safari pre-installed and prominently displayed as the default browser on iPhones. While users can change the default iPhone web browsing app, investigators say that Safari’s designation as the pre-installed default on iPhones reduces user awareness of alternative apps.

Investigators found similar concerns regarding Chrome being pre-installed as the default web browser on the vast majority of Android devices. However, the report notes that both Apple and Google have taken steps to make it easier for users to switch to alternative browsers since the investigation announced its provisional findings in November, which have “addressed some, but not all, of the concerns relating to choice architecture.”

Apple and Google have yet to respond to our request for comment on the CMA’s report.

The CMA has put forward potential remedies aimed at improving competition within the UK’s mobile browser market, which include forcing Apple to allow developers to use alternative browser engines on iOS, requiring Apple and Google to offer a browser choice screen during device setup, and prohibiting the Chrome revenue sharing arrangements between the two companies. These suggestions are currently unenforceable, however, that could change in the coming months.

SMS companies can be imposed with “conduct requirements” intended to address anticompetitive behavior, and risk fines of up to 10 percent of their annual turnover for violating DMCC rules. If Apple or Google are designated with SMS, the mobile browser investigation is encouraging the CMA to “consider imposing appropriate interventions,” similar to the suggestions it outlined. The SMS investigations into Google and Apple are currently ongoing and expected to conclude later this year.

“Following our in-depth investigation, we have concluded that competition between different mobile browsers is not working well, and this is holding back innovation in the UK,” said Margot Daly, Chair of the CMA’s independent inquiry group. “I welcome the CMA’s prompt action to open strategic market status investigations into both Apple and Google’s mobile ecosystems. The extensive analysis we’ve set out today will help that work as it progresses.”