•Crude futures remained firm in European morning trading amid ongoing supply concerns, as renewed violence in Nigeria supported prices after the long weekend on both sides of the Atlantic, sources said. However, despite the bullish sentiment, activity was still subdued in European morning trading, reflected in choppy trading patterns, sources said.

•"There does not appear to be any fresh news around today after the holiday yesterday. The Nigeria [attack] seems to be in the forefront of traders' concerns. Trading is choppy so far with no clear direction today," a London-based broker said.

•Shell said Monday it had shut down some of its production in Nigeria's oil-producing Niger Delta after a militant attack on a flowstation in the southern Rivers state. MEND said in an e-mailed statement that it had sabotaged the Shell pipeline at Awoba flowstation in the early hours of Monday morning and killed 11 soldiers. "There was enough negative production news over the weekend to keep the scarcity worries alive," analysts for Petromatrix said in a report Tuesday.

Updated: May 27, 2008