Officials have warned of a new ‘back door’ illegal migration route opening and a wave of asylum seekers boating to the UK after a group of Iranian migrants arrived on British shores in a rubber dinghy.

The four Iranian men were seen stepping off a ‘rigid inflatable’ vessel by a member of the public in the early hours of Tuesday morning at Dover’s Shakespeare Beach, the Daily Mail reports.

They were arrested on the beach by Kent Police, handed over to border officials, and entered the UK’s immigration system.

According to the newspaper, at least 20 boat crossings and attempted crossings have been reported in the last 16 months. The majority involved migrants from Iran, as well as the Ukraine and Albania.

Conservative MP for Dover and Deal Charlie Elphicke said evidence was gathering that an “Iranian trafficking network” is operating along the route from France.

“The bottom line is that we need to have effective patrols and track down this trafficking network and put the people behind into prison,” he commented.

Just a week earlier, the independent chief inspector of borders and immigration, David Bolt, warned of “clandestine arrivals” and slammed the UK’s weak coastal border patrols and port security.

“The fact that surveillance has been stepped up, both in the Channel Tunnel and the port, means it is possible that they will multiply,” he said.

“The people smugglers want to find new scams. The truck scheme worked well, because it didn’t need any specialist equipment, and it allowed a lot of people to get across at one time.

“But it is getting more and more difficult.’

Similar warnings were made in May 2016, with then-Prime Minister David Cameron promised to invest in extra patrol boats and surveillance to try to prevent migrants crossing the Channel.

UK Maritime Borders ‘Porous’, Protections ‘Dismantled’ – Top Security Expert https://t.co/ZAymJjtMBs pic.twitter.com/V3zrXF3rNx — Breitbart London (@BreitbartLondon) January 5, 2017

Later in 2016, five men, including three Albanians, were indicted for smuggling illegal migrants from Albania across the English Channel to Britain.

The number of illegal migrants detected around ports on the east coast almost doubled to 423 between 2014-15 and 2015-16, a report had found.

As concern grows about sea crossings, the number of attempted land crossings in trucks and trains has remained high and the number of migrants in Calais has begun to rise after last year’s dismantling of the ‘Jungle’ camp.

Earlier this week, figures from France’s interior ministry reveal there have been more than 17,000 attempts to illegally reach the UK by migrants in Calais so far this year.