Her daughter-in-law Ella Woodward posted on social media that the Labour peer was diagnosed in May.

Writing on Dame Tessa's 70th birthday, she described the last few months as "some of the hardest of our lives".

The politician, who stood down as a Member of Parliament in 2015, responded by tweeting her thanks for the "love and support" she had been shown.

Woodward, a food blogger who is married to the politician's son Matt Mills, wrote on Instagram: "Matt's Mum was suddenly diagnosed with brain cancer in May.

"Her bravery, optimism, love and support for others during this process has inspired us both so much, and today we're all pledging to try and do everything we can to make people's lives with cancer better for longer.

First elected as an MP in 1992, she served as Culture Secretary and later paymaster general, and was given a seat in the House of Lords in 2012.

The former social worker played a key role in persuading her Labour Cabinet colleagues to back the Olympic bid, defying civil service advice and even her Cabinet colleagues who were convinced Paris would win.

Jowell convinced the Government to support the bid, however, and went ahead with it. 

In 2004, she officially launched the bid and, when the Olympic and Paralympic Games were awarded to London, she was appointed Olympics Minister and held full ministerial responsibility for the bid from 2006. 

Despite being moved from the Department for Culture, Media and Sport in 2007, she retained her position as Olympics Minister throughout Labour's time in office.

She remained, however, on the 2012 Olympics Organising Committee under chairman Sebastian Coe. 

Jowell was appointed Deputy Mayor of the Olympic Village in recognition for her efforts in getting London the Games.