Carla Lockhart, the MP for Upper Bann, has resigned from the Democratic Unionist Party (DUP) over its handling of the Drumcree parading dispute, saying many in the party agree with her position.

Lockhart left the party after DUP leader Gavin Robinson did not back her call to force First Minister Michelle O'Neill to resign. O'Neill, the Sinn Féin vice-president, was interviewed by police over her involvement in protests on the Garvaghy Road in Portadown, which blocked an Orange Order parade from passing along the mainly nationalist street.

Lockhart told BBC Nolan Live that there has not been this level of "fire" within unionism in recent years. She said unionism has had its head down for too long and that she wants to keep that fire burning.

She said she stepped out of her comfort zone by leaving the party, but she acted to inspire others. Lockhart added that she still respects Robinson and they are friends. She declined to say whether the TUV invited her to join them, though TUV leader Jim Allister said she would be welcome.

Lockhart has said she will continue as an independent unionist in the House of Commons. In an open letter to colleagues, she described forcing O'Neill from office as the only credible option and said a graduated response would be insulting to those who trust the party.

Robinson said he is very sorry Lockhart quit the party. He said the DUP believes O'Neill should face consequences, not the people of Northern Ireland, and that the region needs a functioning government and a budget. Deputy First Minister Emma Little-Pengelly warned that unionism is weakened by infighting and called for unionist cooperation.

Councillor Clement Cuthbertson, a DUP member for 30 years on Mid Ulster District Council, also quit the party this week and will continue as an independent unionist.

Lockhart said her first responsibility remains to the people of Upper Bann and that she will continue to work for them.

The DUP announced last week it would block official engagements involving O'Neill in response to the Drumcree issue, but Robinson stopped short of seeking her removal from office.