VIENNA, March 3 (Reuters) - OPEC oil supply is set to fall slightly in February because of lower output from Iran and Nigeria, a Reuters survey showed on Monday.

OPEC's 12 members bound by output targets, all except Iraq, pumped 29.78 million barrels per day, down from a revised 29.89 million bpd in January, according to the survey of oil firms, OPEC officials and analysts.

The drop reflects lower exports from Iran and supply outages in Nigeria. Some analysts said there were also signs that OPEC members were trimming output to prepare for seasonally lower demand in the spring.

Even so, the survey indicates that OPEC supply remains higher than the group's informal target, offering some relief for consumer countries worried by oil prices that hit a record high of nearly $104 a barrel on Monday.

Output from all 13 members of the Organization of the Petroleum Exporting Countries eased to 32.05 million bpd in February from 32.14 million bpd in January, the survey found. (Reporting by Alex Lawler, OPEC newsroom; editing by Barbara Lewis)