The US has been asked by several trading partners to open up its port services to international competition, a longstanding request given more significance by the dispute over the takeover of P&O by Dubai Ports World.

The request, made in the World Trade Organisation “Doha round” of global trade negotiations, stands almost no chance of success. The proposal is not new, and the US has already ruled out liberalising any port services in the Doha round. But it underlines the sensitivity that even rich nations can have to liberalising service industries, which often leads to foreign companies buying up domestic providers.