Companies listed on the Tokyo Stock Exchange's first section posted a year-on-year increase of 33.2 percent in combined group pretax profit in the first half of the current fiscal year, an economic think tank said Friday.

According to data from 813 nonfinancial companies on their consolidated earnings in the April-September period, combined sales grew 6.3 percent over a year earlier, Shinko Research Institute said.

Growth of both profit and sales was led in part by makers of electronic and electrical equipment, who benefited from strong demand for digital appliances stimulated by the Athens Olympics.

With materials processors, including steel and chemical makers, also performing strongly, manufacturers' combined sales rose 7.5 percent.

Nonmanufacturers, including shipping companies, trading houses and retailers, boosted sales by 4.7 percent.

For the second half of the current fiscal year through March, growth of sales and pretax profit is forecast to slow to 4.1 percent and 9.6 percent, respectively, in light of higher crude oil prices, the yen's appreciation and the uncertain outlook for the global economy.

While electronic and electrical equipment makers forecast a moderate profit increase of 1 percent, transportation equipment makers, including automakers, anticipate a profit decline of 3.8 percent.