LONDON (Reuters) – Online gaming companies have accused Belgium and Greece of keeping them out of their markets illegally and urged European competition authorities to take action. A long-running dispute over licenses in Belgium made headlines last week when Belgian authorities questioned one of the co-chief executives of bwin.party, the world’s largest listed online gaming group. The bwin.party case has underlined the problems faced by companies in the growing online gaming sector when they operate in countries where regulations are unclear or restrictive. Bwin. …