

US base oils exports to Africa rose to a three-month high in February amid a pick-up in shipments to Nigeria.
Exports of 64,370bl (9,070t) to the West African country rose from less than 80bl in each of the previous two months, government data showed.
The most recent cargo shipment to Nigeria had been in November.
There were signs of a further rise in US shipments to Nigeria in March and April.
Most of the February supplies bound for Nigeria were loaded from the district of US Gulf coast district of Port Arthur.
The most recent shipment from that district had been almost a year earlier.