Watch: Jim Anderton's son sings Tom Petty's 'I won't back down' before farewelling father in Te Reo Maori

An emotional son of politician and former Deputy Prime Minister Jim Anderton has sung at his funeral in Christchurch giving a rendition of Tom Petty’s I won't back down.

A large congregation of mourners has gathered at Sacred Heart Catholic Church in Addington to farewell Mr Anderton at a Requiem Mass this afternoon.

Among them is Prime Minister Jacinda Ardern and politicians from across the political spectrum.

Son Chris Anderton fought back tears as he spoke before singing, and he then farewelled his father in Te Reo Maori.

Mr Anderton became a Labour MP in 1984 but after falling out with leadership over economic policy, he established the new Labour Party.

Two new political parties followed Alliance and Progressive, and he retired from politics at the 2011 election.

Mr Anderton died in Christchurch last week aged 79.

The funeral of Anderton, a towering figure in New Zealand's political landscape, was held in Christchurch. Source: 1 NEWS