The leader of the Welsh nationalist party Plaid Cymru has called for devolution in Wales to be scrapped and replaced by a system of self-government determined by the country's citizens.

In what is being seen as the most significant intervention on the future shape of government in Wales made by a Plaid leader since the creation of the Welsh national assembly 15 years ago, Leanne Wood said a new constitution should be written and led by the people of Wales.

In recent years Plaid's leadership has tended to speak about independence as a longer-term aspiration, but with the Scottish referendum putting the issue centre-stage across the UK, Wood said independence ought to be regarded as "normal" and it ought to be up to the people of Wales to decide what powers or decisions are shared with others rather than London deciding what powers the Welsh assembly should have.

Speaking at University College London, Wood said Plaid would now produce a white paper on its plans. She said: "For too long, independence in the Welsh context has been treated as a pipe-dream, as an aspiration so distant it has been seen as unrealistic and unworkable. I want to elevate the debate and I can reveal that Plaid Cymru will shortly be publishing plans to begin the debate on Wales's future."

Wood said a future Plaid Welsh government would seek an agreement with the UK government to devolve the Welsh constitution – including the right to hold binding referendums – to the Welsh assembly. She said this would give the chance for the people of Wales to write their own constitution. "I would be eager for the new process to be people-led, not politician-led.

"Wales's constitution should be written and led by the people of Wales. A citizen-led constitution would help us reinvigorate the politics of Wales generally, it would put power back in the hands of the people rather than with a small elite."

If those constitutional changes were made, the people of Wales would be empowered – if they wanted it – to seek a referendum on independence.

She made it clear that she wanted an independent Wales to continue working closely with other parts of the UK. "We support the establishment of an independent Wales in order to join the international community, not to somehow retreat into an inward-looking isolationism," she said.

"Independence is not an end in itself. It is the beginning of a period of endless opportunity. Above all, independence is normal."