Senior Liberal Democrats and politicians from other parties have praised Sir Menzies Campbell's contribution to public life.

Lib Dem president Simon Hughes said he had "given stability and purpose to our party".

"Ming has made this decision - as all his political decisions - in the interest of his party and Liberal Democracy throughout Britain," he added.

"Every Liberal Democrat owes Ming a huge debt of gratitude."

Acting party leader Vince Cable said: "During his time as leader, Ming has earned the respect, affection and gratitude of the party.

"This was reflected in the warmth with which his speech was received by the party conference three weeks ago. The key message of that speech was that the Liberal Democrats are the only party with the distinctive, positive vision of a fairer and greener Britain.

"Throughout his political life Ming has campaigned for liberal values and social justice and we will ensure that we build on that legacy."

And Mike German, the party's leader in Welsh assembly said: "The party as a whole owes Ming a huge debt of gratitude.

"He has led the re-structuring and professionalistion of the party.

"He offered a strong vision of a liberal Britain and is someone who I along with colleagues in the Welsh Liberal Democrats have a great respect for."

Prime minister Gordon Brown said Sir Menzies "is a man of great stature and integrity who has served his party and country with distinction".

"His contribution on foreign policy and international affairs is valued throughout the world. I'm sure he will continue to make a major contribution to public life," he added.

And Conservative leader David Cameron highlighted his "distinguished parliamentary career" and record as "a fine public servant".

Former Lib Dem leader Charles Kennedy said: "I am sorry that things have ended up for Ming in this way, but know the gratitude felt towards him within the party.

"I don't doubt he has a valuable ongoing contribution to make to the Liberal Democrats into the future."

But SNP Westminster leader Angus Robertson said the move would ""plunge the Lib Dems into further crisis".

"Both north and south of the border the Liberal Democrats are in complete disarray," he said.