Upper Bann MP Carla Lockhart is expected to resign from the Democratic Unionist Party next week following a disagreement over the party's response to Michelle O'Neill's actions during the Drumcree dispute.

In a letter to colleagues on Thursday, Ms Lockhart said she could not support attempts to find a middle ground instead of removing the first minister from office. She described her disagreement with leader Gavin Robinson as a matter of principle and not personal.

The DUP has said it will not collapse the Executive, arguing that doing so would punish the people of Northern Ireland rather than Sinn Féin. Mr Robinson said the party's fundamental position had been decided.

Speaking on BBC Radio Ulster on Friday, Mr Robinson said he hoped Ms Lockhart would not resign and that he understood her position. He said all party members shared anger towards Michelle O'Neill and wanted political sanction for her behaviour.

The first minister recently attended a police interview about her involvement in protests on the Garvaghy Road blocking an Orange Order parade. Mr Robinson said the DUP was pressing the UK Government to bring forward legislation introducing more robust sanctions for Stormont ministers who breach their pledge of office to uphold the rule of law.

Ms Lockhart's letter said the party could legally remove Michelle O'Neill as first minister, even if it could not remove all Sinn Féin ministers and MLAs. She said she had been honest about the limitations of political consequences and criticised the response within the party to concerns she had raised.

It is believed Ms Lockhart will initially sit as an independent unionist MP, though there has been speculation about a future move to the TUV.