The Grand Canal in Venice is one of Italy’s most famous landmarks – but it’s currently under investigation due to something strange in the water.

Police are investigating and environmental authorities are carrying out tests after a patch of bright green liquid appeared in the canal.

The governor of the Veneto region, Luca Zaia, shared a picture of the phosphorescent liquid as it spread through the water near the Rialto Bridge.

He said: ‘The prefect has called an urgent meeting with the police to investigate the origin of the liquid.’

A number of residents reported the strange occurrence, and images shared on social media show the bright green water alongside an embankment lined with restaurants.

Mr Zaia said officials had asked the police to investigate, to see if they could determine who was responsible for the discolouration.

Authorities immediately took water samples, reviewed CCTV and asked local gondolier pilots and boat drivers if they had seen anything suspicious, CNN reports.

Nobody knows what caused the strangely coloured liquid(Picture: Cobra Team/BACKGRID)

The green patch has spread under the Rialto Bridge (Picture: Italian Firefighters/Anadolu Agency via Getty Images)

Andrea Pegoraro, a city councilman, blamed environmental activists, suggesting it may have been caused by the group Ultima Generazione.

They are the group who poured charcoal into the Trevi Fountain in Rome to turn the water black – but they’ve denied responsibility for the green water.

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‘The prefect has called an urgent meeting with the police to investigate the origin of the liquid.’