The Minister for Foreign Affairs has insisted in the Dáil that Minister for the Environment Eamon Ryan's appointment of two people he knew to the Climate Change Advisory Council was not an act of "cronyism".

"I don't accept that this was an act of cronyism at all," Simon Coveney said, defending his Cabinet colleague.

He was responding to Sinn Féin's Matt Carthy, who said: "This isn't about qualifications - this is about process - and there was no process".

The Government has been forced to defend the two appointments to the CAAC since it emerged over the weekend that they were hand-picked.

Professor Morgan D Bazilian is a former special advisor to Minister Ryan, while Dr Cara Augustenborg is a former Green Party election candidate.

There was no open competition for the posts.

Speaking during Questions on Promised Legislation, Mr Carthy suggested that Minister Coveney tell Minister Ryan that "these types of acts of croneyism simply aren't worth it".

Sinn Féin's Pearse Doherty also criticised Mr Ryan for appointing his "two friends" to the council.

Mr Doherty noted there had been a recommendation that an open appointments process be held for the posts.

Minister Coveney should appreciate this, he added, given "the stroke that you tried to pull earlier on in the summer in appointing a former cabinet colleague to a makey-up job".

He was referring to the controversial and ultimately aborted appointment of Katherine Zappone as UN Special Envoy by Minister Coveney.

Mr Doherty said that despite Mr Coveney's promise that lessons would be learned, "clearly they haven't".

"Government appointments should be transparent and they should be open, and it hasn't happened in this instance," he added.

Both deputies called on Mr Coveney to ensure that Mr Ryan appeared before the House to explain these latest appointments.

This week in the Dail, Sinn Féin has repeatedly called for Mr Ryan to take questions on the matter.

The Taosieach Micheál Martin insisted that "it's wrong to impugn the two individuals concerned", who he said were experts in their fields.