The leader of the Welsh nationalist party Plaid Cymru has ventured across the border to suggest that a new party of the left is needed for England.

Speaking in Manchester on Monday, Leanne Wood claimed England lacked the progressive voice that her party provided in Wales.

She said she often gets messages from English people who wish Plaid operated on their side of the border and suggested that the film-maker Ken Loach's proposal for a new party of the left could be a launch pad for a new movement.

"England outside the overheating centre needs a voice, and the left needs a party," Wood said. "In Wales we do have an alternative voice, we have a fourth party that vies for power with Labour and, at the very least, keeps it honest."

Wood said Plaid would like to work with activists in England who wanted to redress the balance of power.

The speech will cause some raised eyebrows. It is relatively rare for a Plaid leader to make a speech in England – and the party's ultimate aim is an independent Wales.

But at an event hosted by the Institute of Public Policy Research North in Manchester, Wood, a former probation officer, said: "I get comments regularly on Facebook and Twitter saying 'I wish Plaid stood in England'.

"Plaid Cymru genuinely wants to support those of you in England who want to rebalance political and economic power. We are not sectarian by nature. We are not consumed by any antipathy to … England."