One of Germany’s most prominent gay politicians has died, aged 54.

Guido Westerwelle, the former chair of the Free Democratic Party, had become the country’s most senior gay politician when his party joined Angela Merkel’s second coalition government.

The leader served as Foreign Minister from 2009 until 2013, and was also Vice Chancellor of Germany from 2009 to 2011.

Mr Westerwelle’s party exited the coalition after the 2013 elections, and the following year it was reported that he had been diagnosed with acute leukaemia.

He passed away today, with his charity the Westerwelle Foundation confirming he had died from complications following leukaemia treatment in a Cologne hospital.

Mr Westerwelle leaves behind his partner Michael Mronz – with whom he made a splash in 2004, when the pair publicly attended Angela Merkel’s 50th birthday party together.

Mr Mronz and Mr Westerwelle registered their partnership in Bonn in 2010, in a private ceremony.

An outspoken supporter of LGBT rights, he long criticized Germany’s lack of adoption rights and full union rights for same-sex couples.

He clashed with finance minister Wolfgang Schäuble on the issue in 2012, after a court ruling demanded the government provides equal tax treatment to gay civil servants and armed forces members.

Westerwelle insisted: “[If] registered partnerships have the same responsibilities as married couples then they should have the same rights. It is not weakening marriage but ending discrimination. We do not live in the 1950s.”