US President Donald Trump has reignited his spat with the world's largest oil producers as surging oil prices take their toll on US manufacturing.
Trump used Twitter to accuse the Organisation of Petroleum Exporting Countries (Opec) of being "at it again", in a fresh verbal attack on the cartel which he blames for the faster than expected oil price recovery.
The benchmark price of crude has surged from around US$50 ($71) a barrel last summer to within a breath of US$80 a barrel a few weeks ago.
The heady market surge is taking its toll on heavy-energy users in the US where the producer-price index rose by 0.5 per cent in May from a month earlier, according to the latest data from the US Department of Labour.