The European parliament's Socialist lawmakers want micro-bloggers to unleash a "Twitterstorm" on the G20 summit host to demand a global tax on financial transactions.

The European deputies are calling on users of the website to send "tweets" to Canadian Prime Minister Stephen Harper, who opposes the idea of a global tax on financial institutions blamed for the worldwide recession.

"Let us remind the world leaders meeting in Toronto for the G20 Summit this weekend, that we want the financial global transaction tax," German European lawmaker Udo Bullmann said today.

"Greedy speculators are responsible for the collapse of the financial markets. In response to the crises, governments around the world have stabilised their economies with taxpayers' money. Now the speculators should pick up the bill," he said.

The message to Harper, he said, should be: "@pmharper: we want a Global Financial Transaction Tax NOW!"

A tax of 0.05 per cent on financial transactions would produce revenue of about one percent of global output, Bullmann said.

European leaders agreed last week to push at the G20 summit for the principle of a global levy on banks and explore a separate tax on financial transactions. Harper's conservative government opposes such taxes.