The US justice department has dropped a price-fixing investigation into Samsung Electronics and Toshiba, the world’s two biggest makers of Nand flash memory chips, the two companies said on Thursday.

When the antitrust case was launched in 2007, electronics analysts suggested the litigation could hamper the ability of big Asian chipmakers to sell their goods in the US, a key importer of Nand flash memory chips for MP3 players and digital cameras.

Investors are also more concerned about semiconductor prices than investigations, Yuichi Ishida, an analyst at Mizuho Investors Securities, told Bloomberg.

Global sales of Nand flash memory, used to store songs and pictures in portable devices such as Apple’s iPhone, could fall 25 per cent to $8.8bn (€6.2bn, £5.3bn) this year, according to estimates by research company iSuppli in April.

Samsung accounted for 37.2 per cent of the market in the second quarter, followed by Japan’s Toshiba with 34.5 per cent, according to Dramexchange, operator of Asia’s biggest spot market for semiconductors.

Toshiba confirmed it had been told proceedings had ended but declined to comment further. It said there was room for growth in the Nand industry as gadgets were becoming increasingly hungry for data storage.

Toshiba has signalled a retreat from the flagging semiconductor industry, which helped to drag it into the red, posting a Y57.8bn ($600m, €430m, £370m) net loss in the first quarter of this year.

Samsung, Toshiba and Renesas Technology , a joint venture of Hitachi and Mitsubishi Electric , said in 2007 they would co-operate with the justice department’s probe. SanDisk of the US, the world’s largest maker of flash memory cards, also received subpoenas, including one for Eli Harari, its chief executive.

Hitachi said in a filing to the US Securities and Exchange Commission this month that the company was informed in July that the justice department was ending the investigation. The statement means Renesas received a notice that it was cleared by the justice department, Hajime Kito, a Tokyo-based spokeswoman at Hitachi, told Bloomberg.

Although the market had been oversupplied, industry analysts now envisage robust price increases for Nand flash memory chips.

That come as further good news for Samsung, the world’s biggest maker of memory chips, which posted its highest profits in two years in the second quarter on the back on brisk mobile phone and flat-screen television sales.

Analysts have predicted that the recovery in memory chip prices could lift Samsung’s third-quarter profits to a five-year high.

Additional reporting by Bloomberg in Seoul