The sale of Henry Moore’s Draped Seated Woman is in doubt after a legal challenge was launched casting doubt on Tower Hamlets council’s ownership.

City law firm Farrer and Co has written to the council suggesting that it is not in a position to sell Old Flo due to question marks over where ownership lies.

The sculpture was originally sold to the London County Council in 1962, before being transferred to the Greater London Council (GLC) in 1964. However, lawyers argue that when the GLC was dissolved in 1985, Old Flo passed to the London Residuary Body – not Tower Hamlets council.

A statement released by the Art Fund said: “Ownership must be established beyond reasonable doubt before a work of art can be sold.

“The council would have surely addressed this before commissioning a sale through Christie’s, and should be easily and quickly able to provide evidence of ownership.”

Tower Hamlets council said it would require up to 14 days to provide documents outlining proof of ownership, and dismissed the legal challenge as a “PR stunt”.

Mayor Lutfur Rahman said: “I have a duty to ensure residents do not suffer the brunt of the horrendous cuts being imposed on us.

“For the Art Fund to challenge our ownership after a period of nearly 30 years seems to be a desperate PR stunt.”

However, opposition to the move remains. The Labour and Conservative groups voted together to pass a motion at last week’s council meeting to postpone the sale, and the Museum of London has urged the mayor to reconsider the decision.

Rushanara Ali, MP for Bethnal Green and Bow, said there are “serious questions” over ownership.

Conservative group leader Peter Golds has also written to the chairman of the Arts Council Sir Peter Bazalgette to request that Old Flo is listed, which would prevent it being exported in the event of it being sold to a foreign buyer.