Thousands of protesters are converging Tuesday on the French Riviera to urge the Group of 20 leading economies to focus on spreading global largesse more equitably instead of saving banks and pleasing financial markets.

Scores of French and international activist groups with a range of missions — from a tax on financial transactions to better environmental protection and fairer labor laws — are organizing protests around the summit of G20 leaders in Cannes on Thursday and Friday.

Their biggest march is planned for Tuesday in Nice, under the slogan "People First, Not Finance." Later they will march on nearby Monaco, known for its friendly tax laws, to urge an end to tax havens.

Bill Gates to join G20 leaders

 Prime Minister Stephen Harper and his G-20 counterparts will host a special guest at their Cannes summit later this week.

Philanthropist Bill Gates will present some ideas on reducing poverty and fostering development in the developing world -- but some of it might not sit well with Harper.

French President Nicolas Sarkozy, who hosts this week's meeting, asked the Microsoft founder to find new sources of financing to tackle food shortages and climate change in the developing world.

Gates is expected to recommend a tax on financial transactions to provide funding for both goals.

But Harper has steadfastly opposed such 'Robin Hood'-style taxation, saying it penalizes Canada's banks for doing well during the recession.

A Harper spokesman says Canada has worked well with Gates on food security and health issues in developing nations, and will have more to say later in the week.

—  The Canadian Press

While some of their goals overlap with that of the Occupy Wall Street movement that has spread to cities around North America and Europe, the protesters in Nice have not latched onto the Occupy name. The protesters here planned their actions many months ago and are pushing agendas that they have long championed.

Security is a major concern for this week's protests. More than 12,000 police and other security officers are deployed to maintain order, with police speedboats stationed in front of luxury yachts in the Riviera harbors and parts of the famed Boulevard de la Croisette in Cannes closed to the public with steel fences.

"We have had a complicated year on the international level what with the death of Osama bin Laden, interventions notably in Libya with an intense and charged sitiuation there. So the terrorist threat level is heightened to a reinforced code red," French Interior Ministry spokesman Pierre-Henry Brandet said.

"Even if the public and the demonstration organizers want the protest to be a peaceful one and to take place in the best possible way, there is nonetheless the risk that on the margins of this demonstration there could be small groups that could infiltrate the demonstration with no other desire than to cause trouble and we're particularly wary of that."

Police in France, where protests and strikes are a common form of public debate and can occasionally degenerate into violence, are well-versed in crowd control and not shy about using tear gas to disperse rowdy demonstrators.

Organizers are expecting between 5,000 and 15,000 people for the protests. Among their leading causes is a push for a small tax on all international financial transactions that would be used for development aid to poorer nations.

But the leaders at the summit are primarily focused on keeping Greece from defaulting and helping Europe overcome its debt crises, which have threatened the global recovery and rocked financial markets.

President Barack Obama is coming to the summit but is expected to take a back seat to French President Nicolas Sarkozy and German Chancellor Angela Merkel because of Europe's problems.