American companies are scaling back plans to hire workers, and a rising share of firms believe the European debt crisis is taking a bite out of their sales, according to a survey of business economists, Reuters reported.

Twenty-three percent of the firms polled in June plan to add to staff in the next six months, the National Association for Business Economics (NABE) said today.

NABE's prior survey, conducted in late March and early April, had shown 39 percent of companies planning to add workers, Reuters said.

Hiring by U.S. companies has slowed in recent months as employers worry about a sagging global economy hurt by Europe's snowballing debt crisis.

Some economic data has suggested that at least some of the hiring slowdown has been due to caution rather than a decline in business. The U.S. Labor Department said earlier this month that companies asked employees to work longer hours in June, even though they slowed the pace of hiring.

According to NABE, 47 percent of companies polled felt their sales have dropped due to Europe's woes.

Among companies that produce goods rather than provide services, the impact was even greater, with nearly four in five reporting a Europe-driven decline in revenues.

Three months earlier, about a quarter of the firms polled thought sales had fallen, Reuters said.

NABE surveyed 67 of its members between June 14 and June 26. About 40 percent of the firms surveyed have more than 1,000 employees.