LONDON/NEW ORLEANS (Reuters) - BP PLC shares fell as much as 4.8 per cent to a 13-year low after the company confirmed that Bob Dudley, a veteran of the company's troubles in Russia, is now managing the crisis response.

Officials had insisted in recent days that CEO Tony Hayward would stay in the front line until the leaking BP well in the Gulf of Mexico was plugged. His position as chief executive is seen as under severe pressure.

'Mr Hayward will remain at the helm for the near term but ultimately, this fiasco might prove career-shortening for him,' said a fund manager from one of BP's top 20 investors on Tuesday.

A series of PR gaffes by Mr Hayward and a failure to quickly stem the leak has piled pressure on the CEO since an explosion on the Gulf of Mexico rig killed 11 workers and ruptured a well, unleashing millions of gallons of crude that still flows into the sea more than two months later.

A US court decision will come this week over whether to uphold a post-spill ban on deepwater drilling in the Gulf of Mexico.

Oil drilling companies are contesting the ban, but it has support among environmentalists and sympathy among fisherman who suffered an extension of fishing bans this week.