The recent oil price rally hasn't been enough to calm the nerves of OPEC kingpin Saudi Arabia.
Speaking at the World Economic Forum in Davos, Saudi Arabia's Energy Minister Khalid al-Falih told CNBC: "I'm still anxious about the fragility of the market (and) about the potential black swans that may spring in front of us. By and large, we are on our way but we are not there yet."
On Sunday, Saudi Arabia's energy minister urged global oil producers to extend their cooperation beyond 2018. Speaking to reporters ahead of an OPEC joint ministerial committee, Khalid al-Falih also raised the prospect of a new form of agreement rather than continuing with the same level of production cuts.
It was the first time OPEC kingpin Saudi Arabia had publicly suggested a new form of coordination among oil producers after 2018.
The current deal, struck by OPEC and 10 other allied producers, is scheduled to last throughout the calendar year. It is thought to have supported the recent oil price rally and helped to clear a global supply overhang.