Carwyn Jones told AMs on the Scrutiny of the First Minister Committee that there will inevitably be times when the UK and Welsh Governments disagree about how much power Welsh ministers have. But he said he hoped those occasions would be 'infrequent.'
He was asked by Liberal Democrat AM Eluned Parrott about a recent decision by the UK Attorney General to refer the Welsh Government's first bill to the Supreme Court.
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A record crowd of more than 66,000 is expected at the Principality Stadium today for the back-to-back Welsh derbies.
The Welsh Assembly election is less than a week away and the treatment and care of cancer is one of the more contested issues.
Tributes have been paid to an ambulance driver killed in a crash with another ambulance in North Wales.