A search was under way Tuesday for 20 crew members missing in the Philippines after their cargo ship ran aground while seeking shelter from rough waters churned up by a typhoon, the coast guard said. 

The crew abandoned the vessel laden with nickel ore on Monday after it hit the shore at Malimono town on the southern island of Mindanao. 

Eighteen of them were still in a life raft when contact was lost on Tuesday, coast guard spokesman Armand Balilo said. The whereabouts of the other two are not known.  

"We had contact until this morning while their life raft was drifting. Search and rescue teams are having a hard time due to strong waves," said Balilo, adding an aerial search was also being conducted. "They reported to the (coast guard) station commander that two members of their crew were separated from them." 

Balilo said they had not received a report on the condition of the Philippine-registered Cebu Great Ocean, which was carrying 2,000 liters (528 gallons) of diesel fuel.