Law firms are having to wait over three months on average to be paid for their services – more than twice as long as most other businesses – new research has shown.

The average period between a bill being issued and payment being received last financial year was 94 days for solicitor firms, according to finance provider LDF. This compares with a UK average of 41 days as calculated by the European Payment Index – a yearly survey of companies across Europe.

This long delay is putting firms under intense financial pressure, warns LDF, whose analysis of over 300 firms included four of the five magic circle members, as well as small and medium size legal services providers.

Travers Smith managing partner Andrew Lilley said the findings showed law firms had to get better at chasing payment.

"If the firm takes a while to issue an invoice it's not surprising it takes a while to get it paid," Lilley told Legal Week. "If there's an efficient invoice going out people have more of a mind to pay it quickly, and I think that's something we want to be more efficient at as a profession.

"Law firms have always been to the bottom end of the class when it comes to that sort of thing. I actually think from our own experience that that period hasn't got any longer since the boom times in the mid noughties.

"Total lock-up periods have actually got better because we have got better at issuing invoices. In the past I would have put the blame as much on the law firms as the clients."

LDF suggest that smaller firms are likely to be worse affected as they tend to have greater numbers of private clients who are harder to chase for fees.

"You tend to find with big firms it's very automated," says Colin Ives, professional services partner at accountancy firm BDO. "It's easier to bill people who are desperate for your services on a very regular basis. The danger is for smaller firms who aren't into the habit of billing as often as they'd like…Private clients don't want weekly bills."

Under rules which came into force last year as part of an EU late payments directive, firms are technically entitled to charge interest and recovery costs – unless any agreement expressly prevents this – if payments from business are more than 60 days late, or payments from public authorities are more than 30 days overdue.