SEOUL, Oct 4 Oil prices eased for a fifth day on Thursday, as a surprise build in U.S. cr

SEOUL, Oct 4 (Reuters) Oil prices eased for a fifth day on Thursday, as a surprise build in U.S. crude inventories overshadowed an unexpected decline in fuel stocks.

U.S. crude fell 21 cents to $79.73 a barrel by 0605 GMT, taking five-day losses to more than $3 a barrel on a rash of profit-taking from near record highs. A recovering dollar and evidence of weaker U.S. demand have fuelled the pull-back.

Brent crude fell 29 cents to $76.90 a barrel.

The U.S. inventory data showed a build in nationwide crude supplies of 1.2 million barrels last week, compared with a Reuters forecast of an 800,000-barrel decline due to expectations of a rise in refinery usage after seasonal maintenance work. S] The fall overshadowed an unexpected decline in U.S.

distillate and gasoline supplies including heating oil, which fell by 1.2 million barrels compared to a forecast of a rise of 1.0 million barrels.

''Traditionally, heating oil inventories should be down by now, while gasoline inventories build up,'' said Lee Mun-dae, crude analyst at the Korea Energy Economic Institute (KEEI).

Gasoline stocks also dipped by 100,000 barrels.

Although the end of the peak hurricane season is near, oil traders remain alert for any signs of bad weather.

Thunderstorms associated with a low-pressure system began moving across offshore production areas, but producers and the Louisiana Offshore Oil Port said they had no plans to shut production or evacuate workers.

Oil had held above $80 for much of the last three weeks despite OPEC's agreement on Sept. 11 to boost output by 500,000 barrels per day (bpd) from Nov. 1. Oil ministers from Venezuela and Qatar have brushed off the need for a further output rise.

REUTERS SR DS1395