Is Argus set to tunnel his way out of mining giant BHP Billiton?

Speculation is rife that Don Argus, the long-time chairman of mining giant BHP Billiton, could announce his departure as early as this week.

Mr Argus, 70, has been in the job since 1999 and is believed to have wanted to step down once the company's $350bn (£245bn) merger with Rio Tinto was completed. But BHP chief executive Marius Kloppers pulled the plug on the deal last year due to the declining market conditions.

Sources close to BHP could not confirm or deny the rumours, but Mr Argus is understood to have said in the past that he would step down once he had reached his seventies. Mining bankers said they had thought he would step down, only to find he had decided to carry on at BHP, which is listed in both London and Australia.

There have also been rumours of discontent at the top of BHP. It has been claimed that Mr Argus wanted to pursue the Rio Tinto merger and disagreed with Mr Kloppers when he decided that the deal had become too costly. However, the duo have presented a united front and are both well regarded by industry insiders.

BHP will announce its half-year results this week. Rival Xstrata launched a £4.1bn rights issue last week, but BHP will almost certainly not follow suit as it has a relatively debt-free balance sheet. The consensus among analysts is that its earnings before interest and tax, and one-off costs such as mine closures, will be $11.6bn for the second half of 2008, up from $9.6bn for the same period the previous year.

Oil major BP also reports results, for the full year, on Tuesday. The market will be keen to see how the group compares to rival Royal Dutch Shell, which posted a record European profit of more than $31bn last week.

Profit at BP for the final three months of the year – like Shell, it announces quarterly results – should be close to £3.1bn, according to Oriel Securities analyst Andrew Whittock.

Pharmaceuticals giant GlaxoSmithKline and British Airways announce full-year and third-quarter results respectively. BA has already announced a profit warning due to the fall in the pound.