Mr Mittal agreed to take on the position of president as opposed to chief executive when steel giants Arcelor and Mittal merged in June.

It was seen as a goodwill gesture to a hostile Arcelor board, which Mr Mittal said could make one of its own chief executive in an effort to overcome opposition to the deal.

Arcelor boss Roland Junck was initially chosen to head the newly merged firm but he has now been replaced by Mr Mittal. Mr Junck will remain on the board as a special adviser to Mr Mittal.

Arcelor Mittal said the changes were made "to clarify the leadership of the company".

It came as Arcelor Mittal posted third quarter profits of 4.4 billion US dollars (£2.32bn) - marginally ahead of expectations in the City and 24% higher than the second quarter.

Arcelor Mittal chairman Joseph Kinsch - who was a leading Arcelor opponent to the merger - said: "We are making these changes to clarify the leadership of the company.

"It had become clear over the past months that the interests of the company were not best served by the previous structure.

"I believe these revised arrangements are in the best interests of all stakeholders. Mr Mittal is one of the most experienced and successful executives in the steel industry and the board is confident his leadership will deliver the considerable potential of Arcelor Mittal."

He added that the newly merged company has made "a very successful start" as it reported sales of 22 billion US dollars (£11.6bn) in the three months to September 30.

Copyright (c) Press Association Ltd 2006, All Rights Reserved.