In other news
Wall Street stocks have opened lower following deep declines in equity markets in Japan and Europe and another drop in oil prices.
The tech-rich Nasdaq has poked into positive territory as US stocks sought to overcome a negative tide that started with a dive in Japanese stocks.
Oil has resumed heavy falls, erasing earlier gains in highly volatile trade, after the International Energy Agency issued a gloomy market outlook.
Nigeria's Dangote Cement share has risen sharply after the firm, majority owned by billionaire Aliko Dangote, announced plans to expand.
British Airways will start offering holiday flights from London Stansted airport, a fourth base in serving the UK capital, putting it in direct competition with Ryanair.
Oil prices may have rebounded off 12-year lows struck last month, but any hope for a broader recovery in the market would be misplaced, says the IEA.
The global oil surplus will be bigger than previously estimated in the first half, increasing the risk of further price losses, as OPEC members bolster production.
European stock markets have steadied at the start of trading after sharp falls the previous session on banking sector worries.