Uncertainty about conflict in the Middle East has left markets on edge over the potential impact on the global oil trade, the International Energy Agency (IEA) said on Thursday.

The war between Israel and militant group Hamas has sharply increased geopolitical risk in a region that accounts for more than one-third of the world’s seaborne oil trade.

“While there has been no direct impact on physical supply, markets will remain on tenterhooks as the crisis unfolds,” the IEA said in its latest monthly oil report.