Video report by ITV News Europe Editor James Mates
Many Iranians hoping to travel across Europe to seek asylum in the UK have been waiting months on Serbia's border with the EU.
Thousands of Iranians took advantage of a 2017 scheme by the Serbian government that offered visa-free travel to them in a bid to boost tourism and trade.
It is thought up to 40,000 arrived in Serbia before the scheme was scrapped late last year.
But many of those who came on a tourist visa had no intention of seeing the sights. Thousands never left and many wait in refugee camps on Serbia's northern border with Croatia, awaiting passage into the EU.
They are hoping to get to Germany, Scandinavia or Britain but many are unable to afford the price - up to €4,000 (£3,600) per person - demanded by the smugglers.
They have fled the oppressive Iranian regime, uprooting families to avoid imprisonment and persecution.
Nushin Kafashhohari has been stuck in Adasevci refugee camp in northwest Serbia with her family for eight months. They can not afford to pay to leave.
She told ITV News two families who paid smugglers €4000 per person had made it safely to Austria and Italy.
Maryam Shishegar was a civil rights activist in Iran who the authorities wanted to arrest and jail. Visa-free travel to Europe saved her and her family.
"As a mother it's very difficult for me to decide to go to prison and to lose your family," she told ITV News.
"I sometimes have a bad feeling about my friends because I wasn't the only person in this situation and I leave them."
The home secretary Sajid Javid declared a major incident last week as the number of migrants making risky voyages on dinghies and small boats across the English Channel rose.
Around 100 migrants - many of them claiming to be Iranians - made the dangerous crossing over the Christmas period, while 230 have attempted to do so since the beginning of December.