Europe's inland and coastal waters have become cleaner and nations such as heavily-indebted Greece and Cyprus boast some of the most pristine bathing spots, according to this year's EU report on water quality, published on Wednesday.

Compiled annually by the European Environment Agency, the latest report on bathing waters finds six nations rated "excellent": Croatia, Cyprus, Germany, Greece, Luxembourg, and Malta.

The three nations with the highest number of poor sites were France and Spain (3 percent of sites in both) and Italy (1.9 percent). In percentage terms, the worst countries were Estonia (6 percent), Ireland and the Netherlands (both around 5 percent).

Some 95 percent of sites surveyed met minimum standards in the report for 2014, an increase of 0.5 percentage points compared with 2013.

Overall the report monitored 21,000 inland and coastal bathing waters across the European Union and in EU neighbors Albania and Switzerland.

Less than 2 percent were rated as having poor bathing water quality, associated with pollution from sewage or agricultural waste, which could cause illness if people swim in it.

A remaining 3 percent were not classified because of insufficient data.

While Europe's waters have become cleaner, the overall state of nature is a major challenge. [Reuters]