A new study from the National Foundation for American Policy shows that U.S. tech companies are relying more on skilled foreign workers using H-1B visas, while Indian outsourcing firms are losing their previous stronghold in the area.

According to the study, four U.S. tech companies — Amazon, Microsoft, Intel and Google — were among the top 10 employers for approved H-1B applications in fiscal year 2017, which ended Sept. 30, and they all saw increases of more than 10 percent from the previous year.

Amazon saw a nearly 80 percent increase in approved H-1B visa applications from the year before, reflecting its growth in the U.S. Facebook saw an increase of 53 percent, and Apple saw a 7 percent increase.

But the overall number of applications is going down, thanks in part to a decrease in applications from Indian outsourcing firms. Immigration attorneys who work with tech companies to file H-1B visa petitions on their behalf say there's also been increased regulation and scrutiny since the Trump administration took over, making the application process more arduous, costing more time and money.

Overall, U.S. Citizenship and Immigration Services received 190,098 applications for the fiscal year that begins in October 2018 (FY 2019) versus 199,000 last year and 236,000 in FY 2017. USCIS gives 85,000 new H-1B visas each year, with 20,000 of those set aside for those with advanced degrees.

The top seven Indian technology companies were given a total of 8,468 H-1B visas in FY 2017 versus 9,356 in FY 2016, a 9.5 percent drop. This follows a massive drop from FY 2015, when these companies got 14,792 H-1B visas.

One of the largest Indian outsourcing firms, Infosys, saw a 49 percent drop between FY 2016 and FY 2017.

NASSCOM, a trade association that represents India-based IT companies, said that in recent years these companies have increased hiring in the U.S. and reduced the number of H-1B visa applications they submit.

NASSCOM adds the increased uncertainty from regulators makes it more difficult to hire foreign workers and "companies will face a choice between shifting more IT work to offshore locations, where larger talent pools are available on better terms; or delaying innovation because of the lack of local talent in the US. Cutting off access to talent will not generate more American growth, innovation, or jobs."