The Arts minister, Alan Howarth, has temporarily barred the export of the two Canaletto oil paintings, valued together at nearly pounds 4m, which are said to be a "unique historical record" of life in the capital. He hopes museums or private individuals in this country will step in before next February's deadline to prevent the pictures from going abroad.
The works in question - View of the Grand Walk, Vauxhall Gardens, and The Interior of the Rotunda, Ranelagh - were produced as a pair during Canaletto's time in England between 1746 and 1756. They have been valued at pounds 3.9m.
The name of the current owner has not been disclosed. It is believed an offer has already been received from an overseas buyer.
Vauxhall Gardens, on the bank of the Thames, flourished under the patronage of Frederick, Prince of Wales. On warm summer evenings, workers and aristocrats mingled as they promenaded, listened to music and dined. The gardens were closed in 1859.
Ranelagh, also situated by the Thames, was a popular site for musical entertainment for the wealthy. The young Mozart performed in the Rotunda on 20 June 1764. The gardens were demolished in 1803.
A spokeswoman for the Department for Culture, Media and Sport said: "The paint- ings are very important pieces of work, not just for themselves but for the his- tory of London. They are a unique record of places which no longer exist."Reuse content