Sussex-based telecoms testing group Spirent has reported pre-tax losses of almost £731 million.

Hekimian, the US-based telecoms company bought by Spirent in 2000, accounted for more than half of £724.6 million-worth of write-offs.

Two other US firms, Zarak Systems and Net-Hopper, were also acquired in the same year and hit by weaker market conditions.

Spirent, based in Crawley, stressed the write-offs were non-cash items and had no bearing on its ability to generate profits.

Annual bottom-line pre-tax losses were £730.7 million, compared with profits of £81.8 million a year earlier.

However, Spirent said its performance at an operating level had been resilient despite an "unprecedented downturn" in the telecoms industry.

Chief executive Nicholas Brookes believed Spirent's performance would continue to be solid in the coming months.

Spirent, which now employs 4,780 people - including 1,200 in the UK - recently cut 700 jobs in a bid to generate annual savings of £34.6 million.