More than half of all British landlords have had tenants abscond before the end of the rental period, research reveals. Unreliable tenants are second only to growing government regulations as the biggest headache for landlords, according to the National Landlords Association (NLA). The problem has grown acute over the past 12 months, with an NLA survey showing that 40 per cent of landlords have had tenants disappear in the past year. 'No matter what precautions they take, many landlords may still find themselves prey to the minority of people out there who are dishonest,' NLA chairman David Salusbury said. 'The UK private rented sector houses a wide demographic spread of people, which includes some of the UK's most vulnerable.' In all, 20 per cent of those surveyed said they had tenants abscond on three or more occasions in the past two years. Hardest hit is the bottom end of the rental market, where demand is dominated by lower income workers, welfare claimants and students. The NLA found tenants often disappeared because debt and redundancy meant they couldn't pay the rent. Personal bankruptcies and credit card debts are rising rapidly. Students leave university owing GBP10,000, on average, in loan repayments. Some drop out of courses because they cannot afford to stay on. Property consultancy Savills warns that the lettings market is becoming unaffordable for many tenants because rents are rising rapidly. Mr Salusbury urged landlords to get written references from their tenants' employers and previous landlords. 'Tenants are much less likely to abandon a property if a landlord has a record of their place of work,' he said. It can be difficult for landlords to reclaim lost rent or damages even through the courts because the tenant may be impossible to trace, the NLA warned. In the middle and top end of the rental market, absconding tenants are few and far between, letting agents have assured. 'National statistics always concern me,' Tim Hyatt, head of residential lettings at property consultancy Knight Frank, said. 'This is not a pattern emerging among our offices. 'It is the cheap and cheerful accommodation where you are going to have a lot of issues, where there is multiple occupation such as housing associations and where you have students, and girlfriends and boyfriends living together. These are going to be different from a corporate tenant or a family looking for a large home.'