Oil prices fell as demand concerns outweighed the prospect of tighter supply from global producers and investors remained sceptical that the US and Iran could strike a nuclear deal. However, there is both upside and downside pressure on prices, amid fears over tighter supply and expectations of higher demand as the US enters driving season being offset by worries over further US interest rate hikes and a slow pickup in China's fuel demand. For the week, both benchmark prices were on track for about 1% losses and for a second week of losses.