Unemployment is rising in Japan as a slide in exports forces firms to curb production, with the tech sector among the worst hit.

Unlike many Japanese companies, Sony does not automatically raise salaries each year based on seniority. Instead pay rises are set annually for each worker based on their role and performance.

"This time we decided to keep the workers' salaries unchanged," Sony spokeswoman Mami Imada said, ahead of the pay round for the financial year starting next month.

Three other Japanese tech companies -- Toshiba Corp, NEC Corp and Hitachi Ltd -- said on Wednesday they were considering similar moves.

The global financial crisis and a strong yen that hit 13-year highs in January is pushing Sony to a projected operating loss of $2.9 billion for the current financial year to March 31.

Sony's shares dropped 1.4 per cent to 1,963 yen on Thursday, underperforming a 0.6 per cent fall in the Nikkei 225 index.

Sony said in January that pay for managers would drop by 10 to 20 per cent through wage cuts and bonus reductions of 35 to 40 per cent.