Slater and Gordon, the world's first listed law firm, has announced more significant losses as revenues continue to fall following its ill-fated acquisition of UK insurance company Quindell's professional services arm in 2015.

The Australian firm – which launched in the UK in 2012 via a takeover of Russell Jones & Walker – has posted losses of A$425.1m (£262.6m) for the six months to 31 December 2016, having previously announced a loss of A$1.02bn (£628.8m) for first half of the year.

The losses included a A$350.3m (£216m) "impairment charge" on the value of its UK business – effectively a write-down.

The firm posted total revenues of A$322.7m (£199.4m) for the six-month period, a 33.8% fall on the previous year's figure of A$487.5m.

In its statement to the Australian Securities Exchange (ASX), the firm said its UK and Australian operations had underperformed "in relation to resolution of personal injury claims".

Group managing director Andrew Grech (pictured) said the results "reflect a business that is still very much in the midst of a major transition", adding that "based on current performance expectation, the continued support of the company's lenders is fundamental, as current levels of bank debt exceed total enterprise value".

The firm said it aims to complete a recapitalisation plan with its lenders by 26 May this year, after agreeing an A$840m (£437m) refinancing deal with its bankers last spring.

In the UK, the firm made savings of £35m, following a 20% reduction in headcount and the closure of 18 of its 48 offices.

However, revenue in Slater and Gordon UK fell to £44.8m, from £54.5m in H1 last year, while revenue in Slater and Gordon Solutions – the former professional services arm of Quindell – fell to £82.9m, down from £110.4m in H1 last year.

In September last year the firm announced that it plans to sue Quindell – now known as Watchstone Group – over the £637m acquisition in 2015.