New South Wales Premier Mike Baird says he is deeply sorry for the way the Liberal Party “let the people of Newcastle down”, after a corruption commission was told of MPs taking cash from prohibited donors.

Newcastle MP Tim Owen and Charlestown MP Andrew Cornwell resigned fro the Party after admitting they had taken undeclared money from donors, including Newcastle Lord Mayor Jeff McCloy.

Mr McCloy told the Independent Commission Against Corruption (ICAC) he had also given money to Swansea MP Garry Edwards, prompting Mr Edwards to stand aside from the Party.

Developers are banned from making political donations under NSW electoral laws.

Mr McCloy told ICAC he was “not a property developer” because he did not lodge development applications.

In a letter sent to a local newspaper and linked from his Twitter account, Mr Baird said: “I am deeply sorry for the way the Liberal Party has let down the people of Newcastle. What hurts me most of all is that the actions of a few have tarnished the wonderful achievements of the Liberals and Nationals in the Hunter Valley since 2011.”

Mr Baird said it was his “solemn promise” to deliver every local project his Government had committed to.

“I will visit the region repeatedly – between now and the election, and beyond – to reinforce my regret at the behaviour of some of our former MPs, and to recommit to the transformative projects we are funding,” he wrote.

“While I lead this state, we will never again let the people of Newcastle down.”