LAGOS (Reuters) -- Some members of the OPEC oil cartel have decided to reduce their crude exports in line with a slow-down in demand after prices fell sharply from record highs, a top OPEC official said on Thursday.

The world's eighth-largest exporter, Nigeria, will cut supplies by 5 percent from Oct. 1, while some other countries in the exporters' club already have trimmed sales, acting Secretary General Mohammed Barkindo told Reuters.

One Nigerian oil industry source said Nigeria, Saudi Arabia and Kuwait were involved in an informal OPEC arrangement to cut supplies and stem the price drop.

Many members of the Organization of the Petroleum Exporting Countries have been pumping near full tilt most of this year, ignoring quotas, as prices soared to record levels. The price of oil has tumbled from a record $78.40 in mid-July, settling in New York at $62.76 on Thursday after falling below $60 a barrel earlier this week.

The sharp price drop prompted OPEC President Edmund Daukoru, who is also Nigeria's Minister of State for Petroleum, to hold consultations with other ministers of the 11-member group.

Barkindo said some OPEC members have decided to moderate exports.

"In Nigeria, there will be a voluntary cut of 5 percent from Oct. 1. There are other members who, even before these consultations, have moderated supplies, medium-sour producers in particular," he said by telephone from OPEC's headquarters in Vienna.

Gulf producers such as Saudi Arabia and Kuwait dominate in the production of medium-sour crude oil, which has a lower yield of high value refined products such as gasoline.

Barkindo said consultations were still underway. Oil ministers are due to meet in person on Dec. 14 in the Nigerian capital Abuja.

The 20 percent drop in prices in two months has many members worried, in particular Nigeria. Daukoru said earlier this week that "something had to be done" to steady the price. A senior OPEC delegate said that "After the steady decline of oil prices during the last week, there were a lot of consultations among OPEC members regarding the market and the necessary action to be taken."