STOCKHOLM, Sweden (AP) _ Sweden's economic crimes unit on Monday launched a preliminary investigation into whether the bookkeeping practices of wireless equipment maker LM Ericsson amounted to tax obstruction.

The focus will be on 2.5 billion kronor ($240 million) worth of 1999 invoices for marketing consultants, which tax authorities considered to be only payment intermediaries, according to the national Economic Crimes Bureau.

The agency will look into whether tax authorities were ``seriously obstructed'' by Ericsson's bookkeeping measures during a review of the company's tax assessment for 2000, which included costs for the mostly foreign consultants, according to a news release.

The tax review disallowed claimed deductions of 423 million kronor ($40 million), which meant an increased tax cost for Ericsson of 120 million kronor ($12 million), chief prosecutor Lage Carlstroem said.

Carlstroem stressed the investigation was in ``its infancy'' and said it was too early to come to any conclusions.

Ericsson spokeswoman Pia Gideon said that the company had not received details.

``We know only of the decision from a press release, and judging by that we feel there is no basis for a preliminary investigation,'' she said.

The Stockholm-based company, which spun off its handset unit into a joint venture with Sony Corp. last year, has been struggling as it faces an industry slump and recorded its first annual loss of nearly 21.3 billion kronor ($2 billion) for last year.