LONDON -- British Prime Minister Keir Starmer on Saturday pledged to detain and send back illegal migrants as the government faces mounting pressure to tackle Channel crossings and the issue of asylum hotels.

"I am clear: we will not reward illegal entry. If you cross the Channel unlawfully, you will be detained and sent back," Starmer said on social media platform X.

His remarks came as several demonstrations were held across England on Saturday, including in London, Skegness and Gloucester, where asylum seekers are being housed in hotels. Five people were arrested in west London.

Thousands had attended protests over the summer, which began after an asylum seeker housed at a hotel was arrested and subsequently charged with several offenses, including the alleged sexual assault of a 14-year-old girl.

The number of asylum seekers being housed in hotels rose to more than 32,000 in the year to June, according to Home Office data. The government had promised to close asylum hotels by the time of the next general election.

Britain and France are trialing a scheme to send migrants arriving on small boats across the English Channel back to France in exchange for the same number of asylum seekers being brought to Britain on a legal route.

But the numbers involved in this scheme are likely to represent only a small fraction of those who arrive. As of July 31, more than 25,000 people had crossed the Channel in small boats in 2025, about 49 percent higher than at the same point in 2024, according to Home Office data.