Reported in the EUobserver here. The African Parliament, and maybe even the African Union may monitor the fairness of elections to the European Parliament. In the article the main controversy seems to involve Zimbabwe and Russia, implying worries that if they send monitors, they may be politically biased.
However, as long as they're independent and fair, this would be a good development; both for Europe, in that it will scrutinise the fairness of the elections, and for the authority and legitimacy of election monitors. A mutual exchange of election monitors could weaken claims of bias and political motivation aimed at weakening the legitimacy of European election monitors when they deliver an unflattering verdict on a country's election.