Shares across the travel sector fell as investors worried about the impact of the Barcelona terror attack on tourism.
Among the airlines, British Airways owner IAG dropped 1.5% while EasyJet fell 0.7%.
Shares in hotel companies were also affected, with Intercontinental Hotels Group down 1.5% and Millennium and Copthorne 3% lower.
By lunchtime, the benchmark FTSE 100 index was down 73.21 points, or 1%, at 7,314.66.
“As we’ve seen over the last couple of years in Europe, these kinds of atrocities affect tourism and will hit airline earnings,” said Neil Wilson, senior market analyst at ETX Capital.
“Investors are concerned that demand will fall over the rest of the year, which was already looking like it would be a tough patch for the industry.”
Randgold Resources was one of the few risers in the FTSE 100, up 1.1%, as the price of gold was bolstered by the metal’s status as a haven in times of uncertainty.
In the FTSE 250, Hikma Pharmaceuticals was the biggest faller, down 5.8%, after HSBC cut its forecast for the company’s share price.
Shares in Hikma had fallen sharply on Thursday after the company said full-year revenues would be at the low end of forecasts,
On the currency markets, the pound edged up 0.1% against the dollar to $1.2875, and was unchanged against the euro at 1.0972 euros.