The banks of the three largest cross-border rivers in northern Greece – the Nestos, Strymonas and Axios – are to be equipped with electronic sensors which will measure water pollution levels and warn regional authorities when they become dangerous, experts said yesterday. This electronic warning system is to be installed along the Nestos and Strymonas by the end of this year and along the Axios by the middle of 2008, Aristotle University agronomy professor Giorgos Zalidis told Kathimerini. The system will be connected to regional authorities’ offices, which will be informed immediately if pollution levels rise so they can take the necessary measures, he said. Of greatest concern are accidents or leaks from manufacturers whose premises are located along one of these rivers. The Axios has suffered the most such accidents to date. The first phase of the project, for the Nestos and Strymonas, is expected to cost -1.1 million.