By Rodney Smith BBC correspondent

Do the Russians want Corus' technology?

Alisher Usmanov has been using his shareholding to press for a seat on the board of Corus.

The company has had its fair share of upsets in recent years - a stormy merger between British Steel and Hoogovens of the Netherlands was followed by failure to merge with one of the huge Brazilian steel groups.

Exactly a year ago, Corus was almost split apart by a row when France's Pechiney tried to buy its aluminium business; that cost it more than $20m.

Speculation?

Since then, the Dutch and British parts of the company have co-existed in an uneasy alliance in which they need one another to survive.

Now Corus finds itself hounded by a predatory shareholder from Russia.

Mr Usmanov bought 5% of Corus in May last year, and recently built that to just under 12%, making him the second largest shareholder.

Corus announces its annual results on Thursday

He has made it clear that he wants to be rewarded with a seat on the board but Corus has kept him at arms length.

He has gained an ally in young, forceful and fast-rising Russian entrepreneur, Oleg Deripaska, himself a former business partner of Roman Abramovich, who runs the Sibneft oil company and Chelsea Football Club.

Mr Deripaska and Mr Usmanov both have steel interests in Russia, as well as aluminium, energy and other interests.

Steel industry observers see them as possible speculators, looking for profits where they can.

Thursday announcement

The Russian steel industry is more than 50%-controlled by three big manufacturers, none of them associated so far with either of the two Russians targeting Corus.

Observers are unable to decide if the Russians are making a concerted effort to ally Corus with their own iron-ore and steel businesses in return for Corus' superior technology.

Or, if as speculators, they are simply buying shares and putting on pressure to ramp up the share price.

This could allow them to exit with a substantial profit.