U.S. chief executive officers are modestly more upbeat about the economy and almost half plan to increase capital spending over the next six months, a business group survey said on Tuesday.

CEOs expect U.S. gross domestic product to rise by 2.8 percent this year, compared to a projection of a 2.4 percent increase a quarter earlier, according to the first-quarter survey by the Business Roundtable.

Of the 120 CEOs who responded to the survey, 45 percent expect to boost U.S. capital spending in the next six months, up from 36 percent in the fourth-quarter survey. Forty percent expect to increase U.S. employment, about the same level as in the prior survey.

"The U.S. economy and the job outlook are starting the year in a stronger position than 2014," said Randall Stephenson, chairman of Business Roundtable and CEO of AT&T Inc.

The Business Roundtable CEO Economic Outlook Index, a composite index of expectations for the next six months for sales, capital spending and employment, rose to 90.8 from 85.1 in the fourth quarter. The long-term average of the index is 80.5.

Eighty percent said they expected their companies' U.S. sales will increase in the next six months, up from 74 percent a quarter ago.

In response to a question about foreign trade, 81 percent said the ability to sell more goods and services to foreign markets would help their company grow and be more competitive globally.