An oil price below $70 a barrel is too low to encourage companies to invest in expensive projects to expand capacity, Qatar's Energy Minister Abdullah Al-Attiyah said on Monday. US crude fell to the lowest in more than three months on Monday, briefly dipping below $70 on concern over Europe's debts, the weak euro and brimming US crude inventories. Investment in new energy capacity worldwide must be maintained to avoid a supply crunch in the future, Attiyah told an industry event, but deep water drilling and other high-cost operations would be unprofitable at a price of less than $70. OPEC-member Qatar supported Saudi Arabia's price aspirations for oil, Attiyah said. King Abdullah, Custodian of the Two Holy Mosques, said in December that a price of around $75 to $80 was fair. “I support fully what King Abdullah says,” Attiyah said. He expected further pressure on oil prices from uncertainty engendered by the European debt crisis.