Emmanuel Macron told Donald Trump late Thursday that tariffs on steel and aluminium imports from the European Union were "illegal" and that the EU would respond in a "firm and proportionate manner", the Elysee Palace said.

The phone call between the French president and his US counterpart came after the US announced the steep metals tariffs would be imposed on the European Union, Canada and Mexico as of midnight (0400 GMT Friday).

Canada hit back at steep US tariffs on aluminum and steel on Thursday, announcing retaliatory duties on up to Can$16.6 billion (US$12.8 billion) in American imports.

Moody's on Wednesday placed a dozen Italian banks and several major companies on negative ratings watch, as the country's political problems drag on.

Amid threats of imminent tariffs on metals and auto imports, escalating trade tensions between Europe and the United States were casting a shadow over a meeting of finance ministers from the world's top economies.

Germany's biggest lenders have shied away from business with Iran after past penalties for breaching US sanctions, but smaller banks have leapt on opportunities afforded by the nuclear deal rejected by Donald Trump.

A 24-hour strike wave hit transports and services in Greece on Wednesday with unions protesting against a new round of reforms linked to the country's concluding third bailout.

The strengthening of the dollar amid Federal Reserve interest rate hikes has sharpened pressure on some emerging economies as investors steer funds to the United States.

Funds dedicated to emerging economy equity and debt saw withdrawals of $569 million and $253 million during the week of May 23, according to data firm EPFR Global.

Azerbaijan inaugurated on Tuesday part of a pipeline complex that will eventually create the first direct route to transport Caspian gas from one of the world's largest fields to Europe bypassing Russia.

Madrid's stock exchange plunged Tuesday led by Spanish banking giants as Prime Minister Mariano Rajoy faces a no-confidence vote later this week, with investors rattled further by political turmoil in Italy.

European stock markets and the euro extended losses Tuesday as political uncertainty in Italy stoked fresh fears about the eurozone.