LONDON, Nov 3 (Reuters) - Handbags owned by late British leader Margaret Thatcher, whose apocryphal use of the accessory as a tactical weapon gave rise to the term "handbagging", are to be auctioned off after a museum rejected them.

They are among 350 "historic and personal lots" - also including clothes, signed copies of speeches, her wedding dress and her red prime ministerial dispatch bag - that auctioneers Christie's said on Tuesday would be offered at its London showroom on Dec 15 and later online.

The sale presented a unique opportunity to buy items from the estate of Britain's longest-serving 20th century prime minister and the only woman so far to have held the office, Christie's said, adding that value estimates ranged from 200 to 180,000 pounds ($300-$280,000).

It noted the term "handbagging" was coined in the 1980s with reference to Thatcher's style in cabinet meetings, and defined in the Oxford English Dictionary as an action by a woman to "verbally attack or crush (a person or idea) ruthlessly and forcefully".

The auction was announced after London's Victoria & Albert Museum, Britain's main repository of historic articles of clothing, said it did not deem the articles appropriate for its collection.

($1 = 0.6487 pounds)

(Reporting by Michael Roddy; editing by John Stonestreet) ((mike.roddy@thomsonreuters.com;))