Conservative news website Breitbart has reported stickers reading “Hillsborough Justice Campaign” and “Justice for the 96” had been slapped on the square’s signage, in reference to 1989’s Hillsborough stadium disaster which saw 96 Liverpool FC football fans crushed to death and 766 injured.
Thatcher, who was UK Prime Minister at the time, was accused along with British tabloid newspaper The Sun of laying the blame on the fans and backing police when the grieving families protested.
The stickers also included the message “Don’t read the Sun”, another indication that the ‘vandals’ were probably from Merseyside as the tabloid is severely disliked there for the poor image they depicted of Liverpool FC fans at the time of the disaster.
On Monday the Spanish capital became the first city in the world to name a square after Thatcher.
Outgoing Madrid mayor Ana Botella unveiled the new plaza on Monday and hailed Thatcher's "commitment to freedom".
The square, in the conservative district of Salamanca, includes a Hard Rock Cafe and a five-star hotel. It has existed for decades but had never previously been named.
Margaret Thatcher, the first female British Prime Minister, died on April 8th last year at the age of 87. Many people mourned her passing but some opponents of 'Thatcherism' held street parties.
Botella described the divisive British politician as "one of the great personalities of the 20th Century" and said that Madrid wished to "recognize Margaret Thatcher by putting her name on this great city".
The Madrid mayor was joined by Madrid PP president Esperanza Aguirre, who is said to view Thatcher as a role model.
Aguirre described the former PM as a "political rebel" while the UK's Ambassador to Spain, Simon Manley, said that Thatcher was "indisputably a great patriot and servant of her country."
Madrid has already planned to name a primary school after Thatcher which led critics to complain when it was announced last year.