Hillary Clinton has unveiled a new political action group that marks her biggest return to politics since being defeated at the 2016 presidential election.

The 69-year-old former First Lady turned Secretary of State and Democratic nominee for president remained relatively inactive after the loss, but said she was inspired by the "remarkable" amount of political activism in the first few months of President Donald Trump's term.

Her new group Onward Together will fundraise for five prominent left-leaning groups as well as encourage greater political engagement.

Announcing the organisation in an email to supporters and a series of tweets on Monday (15 May), Clinton said: "From the Women's March to airports across the country where communities are welcoming immigrants and refugees to town hall meetings in every community, Americans are speaking out like never before.

"I believe more fiercely than ever that citizen engagement at every level is central to a strong and vibrant democracy.

"To support this wave of grassroots organizing, we're launching Onward Together, an organization dedicated to advancing the progressive vision that earned nearly 66 million votes in the last election.

"Onward Together will work to build a brighter future for generations to come by supporting groups that encourage people to organize and run for office."

The group's early efforts will be to fund and support the Swing Left, Emerge America, Color of Change, Indivisible and Run for Something.

"In some cases, we'll provide direct funding to these organizations," added Clinton.

"For others, we'll help amplify their work and do what we can to help them continue to grow their audiences and expand their reach."

In a separate tweet, Clinton said: "This year hasn't been what I envisioned, but I know what I'm still fighting for: a kinder, big-hearted, inclusive America. Onward!"