British Airways shareholders are likely to receive around 60 percent and Iberia investors 40 percent of a new airline when they merge, Iberia's biggest shareholder, Caja Madrid, said on Monday.

The saving bank's chairman, Miguel Blesa, also told reporters that the board of Iberia had unanimously requested a commensurate representation on the board of the new company.

British Airways and Iberia announced their merger plans at the end of July, and last month the UK carrier's chairman, Martin Broughton, said the deal should be wrapped up by March.

Based on the current market capitalization of both companies, the share exchange would have been 33 percent for Iberia and 67 percent for British Airways.

But Spanish media has reported over the last few days that the Spanish flag carrier's shareholders have increased their influence in the merger operation as a result of a pension fund deficit at British Airways.