The number of migrants arriving in Britain by crossing the Channel on boats hit a record in the first half of 2024, but regular immigration by health workers and students fell, official data showed Thursday.

The UK processed 13,489 so-called small boat migrants in the six months, an 18 percent jump year-on-year and the highest figure ever for that period, according to the interior ministry statistics.

That compared to 11,433 migrants making the perilous journey -- across one of the world's busiest shipping lanes -- from January to June in 2023.

The figures are a reminder of the challenge facing the UK's new Labour government as it tries to reduce the cross-Channel arrivals amid public unease over the issue.

The data came in the wake of more than a week of disorder -- dubbed anti-immigration riots -- across England and in Northern Ireland which saw some rampaging mobs chant "stop the boats".

The phrase was an unfulfilled pledge from Conservative former premier Rishi Sunak, who lost last month's general election to Labour's Keir Starmer.

The disturbances, which hit more than a dozen English towns and cities, followed a deadly knife attack on a group of children, an attack wrongly blamed on a Muslim asylum seeker.

However, the number of arrivals of health sector and other workers as well as students and their dependents dropped in the most recent quarter, and year to June.

It coincided with tighter visa regulations announced by Sunak's government last December and imposed in April aimed at lowering record immigration levels.

- More per boat -

Visas issued for health and care workers, a sector suffering from staffing shortfalls, fell by four-fifths from April to June compared to the same period in 2023.

Student visas granted reduced 13 percent in the year to June, and those issued to students' dependants dropped 81 percent year-on-year in the first half of 2024.

Various industry and higher education lobby groups have voiced concerns at the new restrictions, which prevented some dependents from coming to the UK and hiked minimum salary requirements for some workers.

On Channel crossings, the latest figures showed 81 percent of arrivals by people without legal permission to enter the UK in the year to June were on small boats from mainland Europe.

UK officials began counting these "irregular" arrivals in 2018, when there were just 11 in the first half of the year.

Since then, more than 133,000 have arrived -- 70 percent of them men and around a fifth under-18s, according to the data.

Afghans comprised 18 percent of the arrivals in the year to June -- the single largest nationality cohort -- followed by Iranians (13 percent), Vietnamese (10 percent), Turkish (10 percent) and Syrians (nine percent).

The new statistics revealed the average numbers in each boat had increased again, from 10 in the year ending June 2019, 44 in the year ending June 2023 to 51 people in the latest corresponding period.

UK authorities have repeatedly warned that smuggling gangs organising the crossings are adapting their methods, using bigger boats and packing more people in.

Starmer has vowed to "smash the gangs" as the centrepiece of his strategy to tackle the issue, after scrapping contentious Conservative plans to deport thousands of migrants to Rwanda.