Environmental activists from the group Extinction Rebellion poured dye into Venice's Grand Canal and several Italian rivers Saturday in protest against the "failure" of ongoing international climate talks to deliver results.

In the middle of the afternoon, the activists poured a fluorescent green liquid into the Grand Canal, Venice, amid passers-by, gondolas, and tourists, according to images posted on social networks.

At the same time, activists hanging from ropes and harnesses unfurled a banner from Venice's famous Rialto Bridge reading "COP28: while the government talks, we're hanging on by a thread".

Extinction Rebellion Italy said on X, formerly Twitter, that it had sprayed a "harmless" fluorescein dye in the Venice waters.

"The climate crisis is already having a disastrous impact on Italy, science tells us it's going to get worse and politicians are wasting time with farce," the group lamented in a statement.

"We are revolting against this inaction, we cannot remain silent while our future is sold out to the fossil industries!"

Similar actions were carried out in the Tiber in Rome, in a canal in Milan and in the Po in Turin, according to images posted on social networks.

In May, environmental activists painted the basin of Rome's iconic Trevi Fountain black after deadly floods in northeast Italy, which they claimed was a "warning" about climate change.

China said on Saturday it saw progress in reaching a climate deal at a key United Nations COP28 summit in Dubai, despite a last-minute push by the OPEC oil cartel to resist a phase-out of fossil fuels.