The time is evidently not yet ripe for Rio Tinto's management to book its Nixon-in-China breakthrough visit to Beijing. Even if yesterday's warlike comments by a senior Chinese official about the “monopolistic” proposed joint venture between Rio and BHP Billiton carry little weight – and it is, as often, hard to tell – they are a fair indication of the temperature: still red-hot.

Where does this leave Chinalco as it decides what to do with its 12 per cent stake in the UK part of the dual-listed miner? It has three, maybe four, options: dump the whole lot now; renounce its rights to new shares and allow itself to be diluted; take up its rights and sit tight; or gradually increase its holding.

There is no doubt Chinalco and its political masters are still smarting from Rio's decision to drop its planned venture with the state-controlled company in favour of the rights issue and a BHP tie-up.