The attacks in Catalonia may hit tourist numbers, but the recent experience of other European countries hit by jihadist violence suggests it will likely be brief, industry experts said.

Cancellations, early departures, fewer reservations: the impact of a terror attack on an European city can last from three to six months, said tourism professionals.

But the effect is dissipating quicker and quicker, they argue.

"The duration of the effect is shortening as attacks become commonplace" said Jean-Pierre Mas, head of Entreprises du Voyage, an association of French travel agencies.

However the impact can be greater "if there are repeated attacks in the same place," he added.

Didier Arino, head of Protourisme consultancy based in Paris, agrees.

Where there are repeated attacks in the same city, it can end up "appearing dangerous", he said.

That was the case with Paris, which was hit by a series of attacks in 2015 -- including the November 13 attacks on multiple locations in and around Paris, including the shootings at the Bataclan concert venue.

The nation's economic output dropped by 0.1 percentage point in the final quarter of the year.

- Importance of image -

But it is difficult to quantify the overall impact of an attack. 

The number of foreign tourists visiting Britain rose by 7 percent in June from the same month last year, despite three vehicle attacks in March and June in London, the nation's top tourist destination.

"The stronger the image of a destination, the more the impact will be limited," said Arino.

The challenge then becomes for a city to limit the damage to that image.

Arino recommended the use of social networks, in particular the posting of selfies that encourage a "sense of belonging".

That is what the French Mediterranean city of Marseille did after the July 14 2016 attack when a jihadist drove a truck into crowds celebrating France's Bastille Day.

But what doesn't help is refusing to acknowledge the problem, said Arino. "It doesn't do any good to say: 'Our destination is safe'".

For Asian tourists in particular, security is a top issue, said Mas -- and attacks often had a distorting effect on perceptions.

France saw the number of foreign tourists drop by 2 million last year to 83 million, proving a drag on the economy, as tourism accounts for some 8 percent of the total.

- Heightened sensitivity -

"Clients coming from faraway countries like China and the United States have a heightened sensitivity concerning the threat of terrorism and see the situation in a more global context," said Christian Taenzler, spokesman of Berlin's tourism office.  

"They pose the question 'Am I still going to travel to Europe?'"

The answer is often yes.

Despite the attack on Berlin's Christmas market in 2016 the number of Chinese visitors to Germany rose by 15 percent in the first three months of 2017. The number of US visitors rose by 6 percent, according Germany's foreign tourism promotion agency. 

The World Tourism Organization said last month that international arrivals to Europe rebounded by 6 percent in the first four months of the year "as confidence returned to some destinations that were impacted by security incidents".

Tourism consultant Arino believes the effect will be mitigated by the fact that the Spanish economy is growing fast.

"The country is in such a growth dynamic" that the effect will be "less visible", he said.

However tourism accounts for 11 percent of Spain's economy, and has been a key component in helping fuel the country's rebound in recent years.

Barcelona, the top city in international tourism in the world's number two most visited country, according to market research firm Euromonitor International, welcomed 7.6 million tourists last year.

Most of the those visitors came from Britain, France and Italy.

Travel industry heavyweight TUI Group said its clients in Spain were not seeking to go home early. 

"For the moment, we've fielded questions from several clients there, but no requests for an early departure," TUI spokeswoman Susanne Stuenckel told AFP.

She was confident that the attacks would not hit reservations in Spain.