BRUSSELS (Reuters) - Apple ( AAPL ) was ordered by EU antitrust regulators on Wednesday to open up its closed ecosystem to rivals, with the latter spelling out details on how to go about it in line with the bloc's landmark rules and where non-compliance could lead to an investigation and fines.

The move by the European Commission came six months after it opened so-called specification proceedings to ensure that the iPhone maker complies with the Digital Markets Act (DMA) which seeks to rein in the power of Big Tech.

The first EU order requires Apple ( AAPL ) to give rival makers of smartphones, headphones and virtual reality headsets access to its technology and mobile operating system so they can connect with iPhones and iPads seamlessly.

The second EU order sets out a detailed process and timeline for Apple ( AAPL ) to respond to interoperability requests from app developers.

Apple ( AAPL ) slammed the EU order, saying it would hurt users and help its rivals.

"Today's decisions wrap us in red tape, slowing down Apple's ( AAPL ) ability to innovate for users in Europe and forcing us to give away our new features for free to companies who don't have to play by the same rules," the company said in an email.

"It's bad for our products and for our European users. We will continue to work with the European Commission to help them understand our concerns on behalf of our users," added Apple ( AAPL ).

"With these decision, we are simply implementing the law, and providing regulatory certainty both to Apple ( AAPL ) and to developers," EU antitrust chief Teresa Ribera said in a statement.

Apple ( AAPL ) could face an investigation if regulators subsequently find that it has not followed through on the order that could lead to a fine as much as 10% of its global annual sales.