The most bizarre event so far of the third Opec summit in Riyadh, which properly gets under way today, was the accidental broadcast yesterday of about half an hour of the proceedings of the private meeting of energy, foreign and finance ministers, discussing the idea of including a mention of the weak dollar in the summit’s final declaration. The footage was shown on the widescreen TV in the press room, and it is rumoured, right through the TV system in the Intercontinental Hotel, where the meeting was being held, until Saudi officials worked out what was going on - possibly alerted by wire service reports - and rushed to pull the plug.

The most sensitive comments were made by Saud al-Faisal, the Saudi foreign minister, who warned of the danger of a dollar "collapse" if the final statement mentioned the dollar. "Just indicating that we have charged finance ministers with studying this issue … would mean a decision taken by Opec would have the opposite effect and the media would pick up on this point," he said, in Reuters’ translation. "And then perhaps we would find that the dollar had collapsed, instead of us having done something in the interest of our countries."

His point was that any signs the group is further cooling on the dollar as the currency in which oil is priced - and more importantly, in which oil wealth is held - would alarm currency markets and trigger further dollar sales.

It is an embarrassing point to be caught making in public, in part because it carries a suggestion of Saudi politicians defending US interests. But in fact, defending the dollar’s value is an important policy objective for Saudi Arabia for purely selfish reasons. As Adam Robinson and Edward Morse of Lehman Brothers pointed out in a great piece in the FT last month, the weak dollar is already undermining the value of Saudi Arabia’s $800bn in dollar reserves. The Kingdom certainly does not want to weaken it any further.