Japan's Toshiba said Tuesday it fell into a quarterly net loss of $155 million owing to restructuring costs and the impact of a strong yen, but kept its full-year profit forecast unchanged.

The technology and engineering conglomerate said it booked a net loss of 12.1 billion yen ($155 million) for the April-June quarter, reversing a net profit of 470 million yen for the same period last year.

The loss was mainly due to "increased expenditure to promote steady business restructuring for strengthening profitability and the impact of yen appreciation," it said in a statement.

Sales in the quarter fell 4.3 percent to 1.27 trillion yen.

Toshiba left unchanged its full-year forecast, projecting a net profit of 135.0 billion yen on sales of 6.4 trillion yen for the year to March 2013.

In May, Toshiba said its latest full-year profit tumbled by almost half to 73.7 billion yen.

Last year it said it would shut three semiconductor factories in Japan and slow production at a number of other plants as part of a reorganisation of its business, which also includes the manufacture of liquid crystal display televisions.

Electronics manufacturers worldwide are struggling to profit from making televisions amid fierce pricing competition in the overcrowded, low-margin market.

The strong yen has made exporters' products more expensive overseas while eroding the value of foreign-earned profits, amid sagging global demand.

Japanese firms were also pounded by last year's quake-tsunami disaster, and flooding in Thailand, which disrupted operations for firms with plants in the Southeast Asian nation.