Nearly one-in-10 Turks do not regard Islamic State as a terrorist organisation and more than 5 per cent agree with their actions, according to a survey published on Tuesday.

The data was released on the same day as a suspected Syrian suicide bomb attack in the heart of Istanbul’s tourist district which killed at least 10 people and raised fresh fears of Islamist violence in the Nato member country.

The United Nations, including Turkey, brand the group which has taken swathes of land in Syria and Iraq, a terrorist organisation.

The research, entitled Turkey’s Social Trends Survey, was carried out by an Ankara-based think-tank and surveyed more than 1,500 people across the country – a predominantly Sunni Muslim nation – in November.

In response to questions, 9.3 per cent of respondents said that Islamic State was not a terrorist organisation, with 5.4 per cent supporting its actions.

Twenty-one per cent said it represents Islam and 8.9 per cent believe the group is a country or state, according to the research.

The findings paint a picture of a small but significant pool of potential Islamic State sympathisers among Turkey’s 78 million inhabitants.

‘Radicalisation’

Conversely, fears over terrorism, generally and specifically from Islamic State and the outlawed Kurdistan Workers’ Party (PKK), dominated the list of concerns expressed by respondents.

“There are two conflicting positions that we have here,” said Suleyman Ozeren, president of Global Policy and Strategy, the report’s authors.

“But the high number of people supporting Islamic State actions should concern us. It also tells us that prevention of radicalisation policies should be the number one priority for the government. Once people are radicalised it’s very difficult to deradicalise them.”

Turkey has stepped up its fight against Islamists, playing an active role in the US-led coalition bombing Islamic State in neighbouring Syria and Iraq.

Last year it was rocked by two suicide bomb attacks blamed on Islamic State in the southeastern town of Suruc and Ankara, the capital. In the latter, more than 100 people were killed.

Critics have at the same time accused the Turkish government of failing to crack down sufficiently on Islamist networks using Turkey as a route to smuggle would-be jihadists into Syria.

Ankara has also been caught in bitter conflict with PKK militants since the collapse of a ceasefire last July.

The Social Trends Survey covered a range of topics, including President Tayyip Erdogan’s desire to introduce an executive presidency.

Almost 50 per cent said they favoured the current parliamentary system, with 28.6 per cent in favour of a presidential system. More than 22 per cent said they had no opinion or declined to answer.