The leader of the Welsh Liberal Democrats has called for a constitutional convention to campaign for more powers for the Cardiff assembly.

In an article for The House Magazine, Mike German warned that without such a move Labour could ignore calls for further devolution of powers.

The electoral arrangements and powers of the assembly are currently being examined by the independent Richard Commission.

But German said that without a new campaign representing a wide range of Welsh interests, Labour could "file the report on a dusty shelf".

"In one breath, ministers say they do not need more powers, while in the next, they say they can negotiate extra powers as and when they are needed," he wrote.

"They clearly do need additional powers from time to time. It seems that once the assembly government has decided on a course of action, it is content to ask for the power it needs. Sometimes the power will be handed over, sometimes it will not."

German said that Wales would need a body similar to the cross-party constitutional convention that set out the case for a devolved parliament in Scotland.

He said the role of the convention would be to campaign for the Richard Commission's findings to be implemented.

"A convention representing a wide range of Welsh interests would make it difficult for the commission to be ignored," German said.

"Scotland had such a convention in the run-up to devolution and was able to involve a wide range of bodies in the process.

"A Welsh convention would be cross-party and could involve churches, trade unions, voluntary sector, local government, industry and other interested parties."

He added that the cooperation "would provide the political parties with a direct link to all the other groups and individuals who have the good of Wales at heart".

"There can only be benefit - an opportunity for the assembly to win over the minds of the people of Wales and, with others, to make a persuasive case for a Welsh parliament with powers matching those of the Scottish parliament."