NYSE Euronext and Deutsche Boerse have sent proposals to European competition authorities to address their concerns over a merger of the two exchange operators, they said in a statement on Tuesday.

The parties have strengthened their original proposal with respect to European single equity derivatives by increasing the assets to be included in the divestiture, and to provide the purchaser of that business with an option to access Eurex Clearing for single equity derivatives products, the companies said.

The parties have also improved the coverage of their clearing access remedy for innovative equity index and interest rate derivatives, they said.

In addition, they said they would license the Eurex trading system to a third party interested in launching interest rate derivatives.

The European Commission is set to complete its review by February 9, with closing seen in thereafter in early 2012, the companies added.

(Reporting by James Regan; Editing by Christian Plumb)