BRUSSELS, July 29 (Reuters) - Norwegian browser maker

Opera will file a complaint about U.S. tech giant

Microsoft ( MSFT ) to Brazilian antitrust authority CADE on

Tuesday for allegedly giving its Edge browser an unfair

advantage over rivals.

The move underscores the long-running rivalry between the

two companies.

Opera complained to the European Commission in December 2007

about Microsoft's ( MSFT ) tying of its Internet Explorer browser to its

Windows operating system. The case eventually ended with a 561

million euro EU antitrust fine for the U.S. company.

Earlier this month, Opera took the Commission to court for

exempting Edge from the Digital Markets Act, which aims to rein

in the power of Big Tech via a list of dos and don'ts.

In its complaint to Brazil regulator CADE seen by Reuters,

Opera alleged that Microsoft's ( MSFT ) pre-installation of Edge as the

default browser across Windows devices and computers prevents

rivals from competing on the merits of the products.

"Microsoft ( MSFT ) thwarts browser competition on Windows at every

turn. First, browsers like Opera are locked out of important

preinstallation opportunities," Opera's general counsel, Aaron

McParlan, said in a statement.

"And then Microsoft ( MSFT ) frustrates users' ability to download

and use alternative browsers," he said.

Opera, which said it is the third-most popular PC browser in

Brazil, said Microsoft's ( MSFT ) alleged tactics include giving

incentives to major PC manufacturers to pre-instal Edge

exclusively on Windows on all their Windows devices.

Opera also alleged that Microsoft ( MSFT ) uses anti-competitive

measures such as design tactics or dark patterns to steer PC

users away from rival browsers to Edge.

Opera called on CADE to investigate Microsoft ( MSFT ) and to demand

concessions to ensure fair competition.

(Reporting by Foo Yun Chee; editing by Matthew Lewis

)