'The law states that the arbitrators have to consider the economic situation,' he said.

'But judging by their conclusion, they clearly did not take that into account.'

Francis Lui Ting-ming, an economics professor at the University of Science and Technology, will submit a written testimony to argue against the decision.

He said the New Harbour Tunnel Company should not be allowed a 15 to 17 per cent internal rate of return when the economy had been performing poorly in recent years.

The arbitrators were wrong to have concluded that the economy was doing well simply because the Hang Seng Index had been at about the same level as 1997, Professor Lui added.

'They are economic illiterates,' he said of the arbitrators. 'I'm talking about Economics 101. A lot of people understand this, but not the two British lawyers [who acted as the arbitrators].'

The plaintiffs of the case, Chan Yu-nam and Poon Tat-keung, are taxi drivers based in the eastern part of Hong Kong and Kowloon who often have to take the tunnel.

Their income had declined since the toll increase kicked in, said Wong Tai Sin district councillor Andrew To Kwan-hang, who also helped file the case.

The drivers will be represented by senior counsel Philip Dykes.

Mr Kwan admitted that he did not have much confidence after the court's decision yesterday to throw out the Link Reit case, also a judicial review application.

'I don't have that much confidence after the Link case,' he said. 'But we never say die.'

Other legislators who helped the case were Albert Cheng King-hon and 'Long Hair' Leung Kwok-hung.

Mr Kwan said they would try to raise more money to fight the case.