The London Chamber of Commerce says the disruption is causing companies at least �9m per day due to time lost getting to work and cancelled meetings.

And Dirk Patterson, spokesman for the chamber said it will cause "incalculable" damage to the city's tourism.

Patterson: Long-term cost to economy will be high

Mr Patterson said the long-term damage to the economy will also be high.

"There will be people who stop investing in London, international businesses who relocate, because they just think London does not work," he said.

The chamber is also worried about the tourism industry.

Popular tourist sites have seen drastically reduced numbers of visitors on Thursday.

Mr Patterson said 14 million tourists a year visited London, a number which would be severely reduced because of the strike.

We are already hearing reports of people going home right across the world ... saying to their homelands: 'don't go to London'

Dirk Patterson

He said: "People are saying 'don't bother going to London, its a mess, they cannot run their transport system'.

"We are already hearing reports of people going home right across the world, from America to far flung parts of Asia saying to their homelands: 'don't go to London'.

"It is very damaging indeed."

Jeopardising safety

Mr Patterson said 87% of chamber members want to see a no strike agreement reached, to avoid a repetition of Thursday's day of action.

The Rail Maritime and Transport (RMT) union, which called the strike, is against government plans to bring in private engineering companies to modernise the Tube.

It claims using private companies to do maintenance work will be safety in jeopardy.

Mr Patterson said: "Of course we agree safety is paramount.

"But we want to see a no strike agreement and sensible discussion being the way forward with these matters."

He said the chamber believed the RMT union had "hijacked" the issue for their own ends.