Image copyright Anadolu Agency Image caption Some of the nine British nationals who were detained by Turkish security forces as they allegedly tried to cross the Turkey-Syria border

Nine British nationals have been detained in Turkey after allegedly trying to enter Syria illegally.

The group, reported to be three men, two women and four children aged from two to 11, was held at Reyhanli, in Hatay province, near the Syrian border.

Their intention in travelling to the region, where areas are controlled by Islamic State (IS) militants or an al-Qaeda affiliate, is not clear.

The Foreign Office has said it is in contact with the Turkish authorities.

The BBC's Mark Lowen said the information about the ages of the children had not been independently verified and it was too early to know where the group were intending to head to.

"Were they heading for one of the more moderate groups in Syria. Were they heading for the area controlled by al-Nusra, the al-Qaeda affiliate? Or were they heading to so-called Islamic State territory?" he said.

The group was taken to a police station in southern Turkey overnight, and then sent to the foreigners department awaiting deportation to the UK.

They have undergone medical examinations and had their finger-prints taken.

'More effective measures'

The United Nations estimates the number of foreign fighters joining militant groups is more than 25,000, from 100 different nations.

About 600 Britons are believed to have gone to Syria or Iraq since IS seized control of large swathes of territory there.

Most are thought to have volunteered as fighters for the militant Islamist group.

Around half are believed to have later returned to the UK, the Metropolitan Police has said.

The latest detentions come two weeks after three British teenagers were stopped from travelling into Syria from Turkey.

The three - two aged 17 and one 19, from north-west London - were arrested following a tip-off from British police and flown back to the UK. They have since been released on police bail.

They had flown to Turkey from Barcelona and were arrested at Sabiha Gokcen airport in Istanbul.

Image copyright Reuters Image caption Turkey says it has taken steps to reinforce its border with Syria

Fadi Hakura, Turkey analyst for Chatham House, told BBC Radio 4's Today programme the recent arrests showed the Turkish government was "taking more effective measures to control the flow of fighters and supporters into Syria".

He said there was now "more enhanced security and intelligence cooperation between Turkey and its Western counterparts, especially with the exchange of names that Turkey needs to prohibit [IS supporters] from crossing into Syria".

The Turkish government has said it cannot make a 560-mile border watertight and will act when it has prior warning.

In February this year there were recriminations between British police and Turkish officials after three London schoolgirls disappeared from Turkey, apparently having crossed the border into Syria.

Shamima Begum, Amira Abase, both 15, and Kadiza Sultana, 16 had flown to Istanbul and travelled to the border region.

Turkish officials said they had not been warned promptly enough by British police to intercept them - Scotland Yard denied this.