In other news
Zambia will maintain a mineral royalty tax despite fears it could lead to mine closures, President Edgar Lungu said as he was inaugurated in the nation's capital.
With oil prices tumbling, Britain's North Sea oilfields face a struggle for survival, threatening a vital source of income and energy.
Gary Cohn has urged the UK to stay within the European Union, warning, ahead of a May election, that an exit would put the capital's status as a major financial centre at risk.
US stocks have dropped modestly, pressured by some disappointing results from major multinational companies.
Russia may have to spend more than $40bn this year to avert a banking crisis, as the growing likelihood of a sharp recession looms.
Greek leftist leader Alexis Tsipras has dismissed suggestions that Athens has to complete a review of its international bailout by the end of next month.
The World Health Organisation is set to run out of cash in mid-February, a senior official says, as the organisation prepares to mobilise before the rainy season hits in April.
The European Central Bank's bond-buying programme must not be used as a justification by eurozone governments to slacken economic reforms, says German Chancellor Angela Merkel.