An attacker on Sunday threw firebombs at an immigration office used to process asylum seekers crossing the Channel in small boats as the government seeks to curb record arrivals.
Kent Police said that on Sunday morning "two or three incendiary devices" were thrown into a centre processing immigrants in the Channel port town of Dover in southern England, injuring one.
The BBC quoted the Home Office as saying the attack took part at the Western Jet Foil Border Force centre in the major Channel port town, used to process asylum seekers.
Police said that "one minor injury has been reported" and the suspect "has been identified and located", without giving further details.
Kent Live local news website posted photographs of police and fire services at the scene near the Port of Dover, and the BBC reported that a fire was put out.
Immigration Minister Robert Jenrick tweeted that there had been a "serious incident" and "my sympathies are with those involved".
Dover's Conservative MP Natalie Elphicke tweeted: "I am deeply shocked by the incident in Dover today. I have spoken to the immigration minister (Jenrick) about the situation. My thoughts are with everyone involved."
Elphicke later told LBC Radio: "I understand that the Dover immigration centre that is at the Port of Dover was firebombed by a number of devices before an individual committed suicide."
Police have not confirmed reports that the attacker killed themselves.
The local MP said that the attack took place at a centre where people arriving in small boats are initially taken before going to Manston, another processing centre in Kent.
- 'Tensions running high' -
Elphicke told LBC: "We don't know the motivation of the individual concerned yet."
She added: "I think it is fair to say that tensions have been running high over the last period".
She cited a case where immigrants arriving in a small boat had entered a resident's home.
Government figures showed that 990 migrants crossed the Channel in small boats on Saturday, bringing this year's record total to nearly 40,000.
The issue has caused a major political headache for the UK government, which promised tighter border controls after leaving the European Union.
Interior minister Suella Braverman has backed a plan for migrants crossing the Channel illegally to be sent to Rwanda, while this currently faces legal obstacles.
Elphicke wrote an article in the Mail on Sunday headlined: "When will the Left admit this is no refugee crisis... but simply illegal immigration".
UK Prime Minister Rishi Sunak said Friday that in his first call in office with French President Emmanuel Macron the leaders agreed on greater cooperation to "deter deadly journeys across the Channel that benefit organised criminals".
Sunak has called for the Channel route to become "unviable" for people traffickers.