Hundreds of people took part in a Global Divestment Day protest in Sydney today and serenaded an appeal to the Commonwealth Bank of Australia to stop funding coal expansion in the Great Barrier Reef World Heritage Area.

Singing a modified version of "Stop in the Name of Love" on the eve of Valentine's Day, the protesters targeted the Commonwealth Bank, one of the four major national banks, to urge them not to fund Adani's Carmichael mine and Abbot Point coal port in Queensland.

Expansion of the port of Abbot Point is planned to provide export facilities for coal mined from the Galilee Basin, where some $190 billion in new coal alone is in various stages of development. A second wharf and ship loader are being installed.

Greepeace said this threatens to destroy the Great Barrier Reef.

Once completed it would be the largest coal port in the world, surpassing the Port of Newcastle 1,500 km to the south.

Germany's Deutsche Bank last year declared it would not finance expansion of the Abbot Point coal shipping terminal near the Great Barrier Reef, responding to calls from green groups and tourism operators.

While green groups have raised a string of legal challenges against the coal projects, they are stepping up their campaign ahead of a Unesco decision on whether to put the Great Barrier Reef on its endangered list.

If Unesco's World Heritage Committee in June deems the reef to be in trouble, that could result in big restrictions on ports and shipping in the area around the reef.

The Australian government says it should not be deemed in danger as no reef species have become extinct, and some, like humpback whales and loggerhead turtles, have recovered from big declines.