The leader of the Welsh nationalist party, Plaid Cymru, has described as "illogical and perverse" the suggestion that voting yes to Scottish independence represents a failure to act in solidarity with the people of England and Wales.

Speaking to the Guardian, ahead of a lecture on Tuesday evening hosted by the Radical Independence Campaign, Leanne Wood said: "For me solidarity through divergence is a better way of showing people outside of Scotland what is possible."

Wood warned the Scottish electorate not to trust Westminster parties' promises of more powers in the event of a no vote. "The only way that people in Scotland can be guaranteed additional powers is if they vote yes," she said.

Wood will call for Scotland to become a "beacon" of social justice to counter the "spiteful rightwing rule" of the UK government.

Plaid sees the independence debate in Scotland as a chance to restate its long-held position that Wales ought to become independent. Many inside and outside the party believe that if Scotland does become independent it will lead to a reassessment of whether Wales ought to follow suit.

Wood told the Guardian: "[A vote for independence] is not about being better or superior in any way, it's just about having the opportunity to forge a set of politics that is closer to the values of people here, which are different." She said the same was the case for Wales. "If you look at elections over a period of time people here and in Wales tend to vote to the left of people in England and democracy is about having the politics that you vote for."

In her lecture, Wood will say:"Scotland gives us in Wales and our progressive friends in England opportunities to point to demonstrable examples of an alternative to neoliberalism and the politics of austerity.

"Just imagine what we could point to if Scotland emerges as an independent country. Having a new state on our doorstep approaching public services in a different, more progressive way compared to what will be left of the UK. Pursuing collaboration not competition.

"The greatest act of solidarity people in Scotland can show to us, in Wales, is to create in your nation a society that rejects the poison of spiteful rightwing rule and build instead a socially just country that will show the way for us all as a beacon in these islands."

Last month Wood called for devolution in Wales to be scrapped and replaced by a system of self-government determined by the country's citizens.

In what was 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, 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, 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.

Wood said that if there was a similar campaign for Welsh independence, she hoped it would reflect the broad span of the Scottish movement. "I would very much hope that we would have a similar grass roots movement operating outside of the traditional parties. It's enriched the debate here in Scotland and it has the potential to strengthen political parties as well because people are engaged in a way that they weren't before."