Anti-austerity left-winger Jeremy Corbyn's crushing win to become leader of Britain's opposition Labour Party could divide his party's MPs but give a boost to its grassroots power, commentators said on Sunday.

The veteran socialist's victory with 59.5 percent of the vote also marks a break with the legacy of controversial former prime minister Tony Blair and his centrist "New Labour" movement of the 1990s.

"Death of New Labour," read a headline in the front page of the Sunday Telegraph.