The platform is part of the European Commission's strategy to increase co-operation between European police forces when tackling child porn, malware, spam and identity theft on the web.
The strategy will also include police "cyber patrols", joint investigation teams, remote searches, and closer co-operation and information exchanges between law enforcement authorities and the private sector.
The alert platform will be used to share reports on crime committed on the internet, such as the posting of illegal content.
European Commission vice-president Jacques Barrot said, "The strategy encourages the much needed operational co-operation and information exchange between the member states.
"It gives a shared responsibility to the Commission, the member states and other stakeholders to introduce the different measures. If the strategy is to make the fight against cyber crime more efficient, all stakeholders have to be fully committed to its implementation. We are ready to support them, also financially, in their efforts."