Media bosses concerned about long-term impact as billions lost in wake of London terror attacks

"This will cause people to want to pull the covers over their heads and that affects the economy in more ways than one, and could have a dampening effect."

The attacks wiped billions off the value of British companies, with all of the FTSE's top 100 firms falling sharply as investors panicked.

The biggest losers were companies associated with the tourist trade, including British Airways. At one point, the FTSE was down as much as 200 points, or £50bn, before recovering somewhat.

Retail analysts are waiting to see the impact it will have on shoppers as shops hope that nervy consumers are not tempted to stay away.

In the short term, the impact of the London terrorist attacks, which have so far left 38 dead although unofficial numbers quoted now stand at 52, and hundreds injured, has been significantly less than the September 11 2001 attacks on New York and Washington. In the aftermath of that tragedy, networks pulled all advertising from television, and it was some time before normal programming resumed.

But last night in the UK, broadcast schedules continued largely as normal, with extended news coverage on most networks.

Nonetheless, in the US, Viacom's co-chief operating officer Tom Freston also said he was worried about the long-term impact.

"It probably will have an impact, these things usually do to some extent," he said.

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