Only a small proportion of the applicants are detained - currently 720 are locked up in prisons and detention centres. But this is a record number, and it is rising.
Civil rights groups are extremely critical of what they believe is the increasingly arbitrary use of detention for would-be immigrants and prejudice against people from certain parts of the world, particularly Africa and Asia.
They have also condemned the time it takes for applications to be processed - more than a year in some cases. The vast majority are turned down - in 1992 about 1,000 out of 35,000 applications succeeded.
The Home Office argues that it follows strict rules and guidelines in the treatment of asylum-seekers and only uses detention as a last resort.
A claim for political asylum is usually made to the immigration officer at the port or airport, but it can be made at any time. The immigration service has to decide whether to detain the applicant or allow them into the country while they are assessed. The basic rule for detaining someone is whether the immigration service believes the person will abscond or go into hiding.
Under the 1971 Immigration Act, certain groups are more likely to be locked up: those who have previously applied for asylum or illegal entrants caught trying to smuggle themselves into the country; those caught working illegally; and those who have had their application rejected and are about to be deported.
To gain refugee status a person has to prove a well- founded fear of persecution, usually because of religious or political beliefs.
Applicants have to go through a series of questionnaires with immigration officers. The results are examined by the Home Office which decides whether the person is allowed to stay.
Among the 700-odd asylum seekers in detention the most common countries of origin are India, Ghana, Turkey, Nigeria and Algeria. Amnesty International has issued reports on all these regions, describing civil wars, political turmoil, dictatorship, and the widespread torture and murder of members of opposition parties.Reuse content