Shareholders in lithium producer Allkem have been urged to vote in favour of a $9 billion merger with US company Livent, with influential proxy adviser Glass Lewis saying a slump in valuations for the producers should not derail the deal.

The plan to create the world’s third-largest lithium producer by volume has been called into question in the past month by some fund managers who believe Allkem shareholders should emerge with more than the slated 56 per cent of the combined group.