LONDON, Jan 21 (Reuters) - West African crude price differentials were stable on Tuesday as traders await Angolan March offers and Nigerian March loading schedules this week.

* Traders were awaiting term allocations and first offers for Angola's March loading schedule at the start of this week, trade sources said.

* Angola will load 32 crude oil cargoes in March, the country's preliminary loading schedules showed, up from 28 in February.

* Angola's exports were pencilled in at 993,000 barrels per day (bpd) for March.

* Offer levels for West African crude grades have risen in recent weeks, with sellers anticipating firmer demand as buyers in Asia seek alternative supplies to Russian and Iranian grades after new U.S. sanctions.

* But steeper backwardation, higher freight costs and looming spring refinery maintenance could be providing a ceiling to buying interest in the wake of higher offers, a trading source added.

* Nigerian Bonny Light was last heard on offer at dated Brent plus $2.20 a barrel, up more than $1 from the last offer level heard, a trader said on Friday.

* Nigerian environmentalists on Tuesday condemned a government plan to resume oil production in restive Ogoniland, demanding a halt until meaningful talks with local communities are completed.

* An oil spill at a wellhead and subsequent fire in Buguma community in Nigeria's coastal Rivers state has entered its fourth week, with no immediate action taken by authorities or operators to halt the destruction, rights groups said on Tuesday.

(Reporting by Robert Harvey Editing by David Goodman )

((Robert.Harvey@thomsonreuters.com; +447552256587;))