No immediate claims of responsibility for incident.

Venice authorities were left puzzled on Sunday after a section of the Grand Canal near the Rialto Bridge turned a fluorescent green, Italian media reports.

The mysterious incident was reported to police at around 09.30 on Sunday morning, with tests carried out by experts from the fire service and the regional environmental protection agency ARPAV.

In a press release, Venice police said the discoloration appears to be from a "tracer dye", commonly used to detect leaks and monitor water flows, however the source of the liquid remains unknown.

Una chiazza fluorescente ha colorato di verde parte del Canal Grande e della laguna a #Venezia: prelievi e assistenza tecnica da parte dei #vigilidelfuoco agli operatori dell’@arpaveneto che stanno conducendo analisi per stabilire la natura della sostanza in acqua#28maggio pic.twitter.com/vgmUeRthKK— Vigili del Fuoco (@vigilidelfuoco) May 28, 2023

Police added that no group or individual has claimed responsibility for the incident, however based on tests carried out by experts the affected water does not pose a public health risk.

Investigations and tests are ongoing in an attempt to determine the origin and exact nature of the green liquid.

Photo Vigili del Fuoco