WASHINGTON—The Trump administration is demanding supporting evidence in many more applications for coveted H-1B visas for high-skilled foreign workers, and denying more petitions, according to its own data published Friday.

The number of requests for evidence by the U.S. Citizenship and Immigration Services, which administers the visa program, has grown as the administration has sought to overhaul the immigration system.

Some 60% of companies that applied on behalf of foreign workers received requests for supplemental information in the last quarter of 2018, compared with about 46% of applicants who got the demand in the year-earlier quarter and 28% in the final quarter of 2016. The approval rate fell to 75% in the final quarter of 2018, from 83% a year earlier and 92% in the same period in 2016.

The data included companies seeking to extend visas for current employees, as well as applications for prospective new hires.

USCIS director L. Francis Cissna, who started in his position in October 2017, has pledged stricter vetting in the immigration system and policies that he said would protect the interests of U.S. workers.