The two works were first spotted on the walls of the Barbican earlier this week, ahead of the opening of the Basquiat: Boom for Real exhibition tomorrow, 21 September 2017. Banksy – the famously anonymous street artist – confirmed he was behind them via his Instagram account.
The larger of the two pieces appears to be Banksy's own take on Jean-Michel Basquiat's Boy and Dog in a Johnnypump, created in 1982.
It depicts a figure being frisked by two police officers, and is captioned with "Portrait of Basquiat being welcomed by the Metropolitan Police – an (unofficial) collaboration with the new Basquiat show."
The second artwork shows people queueing for a ferris wheel adorned with crowns – a common motif in Basquiat's artwork – instead of passenger carts.
The caption seems to mock the Barbican's motives for holding a retrospective of works by Basquiat, who started out as a graffiti artist. It reads: "Major new Basquiat show opens at the Barbican – a place that is normally very keen to clean any graffiti from its walls."
According to the BBC, City of London officials have not yet decided what to do with the two works.
"We plan to discuss the pieces with City Corporation colleagues and Barbican residents over the next few weeks," a spokesperson told the BBC.
Basquiat was an integral part of the New York art scene from the late 1970s until his death in 1988 at the age of 27. Although most famed for his paintings, his unique output spread across many other areas of popular culture, including graffiti and music.
The retrospective, which opens at the Barbican tomorrow, is the "first large-scale exhibition" of the artist's work in the UK, and brings together over 100 pieces from global museums and private collections.
Banksy meanwhile is known for producing politically charged works that support causes he believes in. He recently opened an "all-inclusive vandals resort" in Bethlehem, five metres from the wall that separates Israel from the Palestinian West Bank, and created a mural in the English town of Dover, showing a worker chipping a star away from the European Union flag.
Previous works by the artist have included the temporary "bemusement park" of Dismaland in Somserset, the remains of which the artist eventually transferred to Calais.