AMSTERDAM, March 12 (Reuters) - A threat by the Netherlands' largest company ASML to quit the country if it cannot grow there has laid bare wider corporate concerns that the nation's business climate is deteriorating.

While the semiconductor equipment maker's CEO has since ruled out a total departure from the Netherlands, a Reuters review of Dutch blue chip firms has shown that ASML is far from the only one considering its options.

After corporate tax increases and protests and court cases against Shell and others in recent years, populist parties booked big gains in 2023's national elections. That has prompted companies to speak out against policies that would discourage immigration and force them and their investors to shoulder more taxes.

Such policies may appeal to voters, but ASML and other tech firms that depend on foreign staff argue that they undermine the country's future prosperity. With the rise of far-right parties across other European countries, similar concerns are being voiced in Germany, where CEOs from Infineon to Volkswagen have warned about the threat of right-wing extremism to the country's economy.

Dutch blue chip firms also say plans to tax share buybacks, limit investment deductions and gut innovation funds are being pushed through without considering the consequences, especially at a time when other countries are courting foreign investment.

"Many stock market-listed companies are investigating moving their head office to another country," Ingrid Thijssen, the head of the country's largest industry group VNO-NCW told Reuters.

"You'd need two hands to count them."

That chimes with a January study by SEO Economic Research commissioned by the Finance Ministry that found a third of Dutch multinationals would consider moving operations abroad in the next two years.

The government has now launched an all-hands effort code named "Project Beethoven" to persuade ASML to stay, including looking at ways to "undo the harm" of ending a tax break for skilled migrants.

"If we want to keep companies in our little country, we will have to really work harder," Economy Minister Micky Adriaansens told Reuters.

More than a dozen companies responded to Reuters questions asking if they were concerned about the national business climate and would consider moving their operations.

Though only a handful said they would consider relocating their headquarters, some, including heavyweights Shell and Unilever, already have. Others said they are prioritising foreign expansion. All, including the country's main financial and industrial firms, said they were worried about predictable government policy making, essential for business.

Jean Schreurs, the head of the Dutch branch of semiconductor maker NXP, echoed ASML's concerns over immigration restrictions.

While anti-Islam law maker Geert Wilders negotiates a government with other parties opposed to immigration, parliament has adopted a motion to cap the number of foreign students allowed to study at Dutch universities as well as end the skilled migrant tax break - both important pipelines for skilled labour.

"If people feel they are not welcome... the Netherlands will not be the top country that they look at," NXP's Schreurs told Reuters, adding that the country's reputation is still generally good.

"I think we need to be careful of throwing away everything we've built up in all these years."

Chip equipment supplier ASM International recently expanded in the U.S. state of Arizona, and BE Semiconductor Industries in Vietnam. Payments firm Adyen said it is prioritising hiring at its offices around the world over its Amsterdam seat.

Dredging company Boskalis - which helped relieve the 2021 Suez Canal blockage - said it is considering moving its headquarters to Abu Dhabi. The company pointed to remarks made by CEO Peter Berdowski on an NOS radio program on Thursday.

"The only thing that I've seen is that the scales are tending to weigh against the Netherlands," Berdowski said, citing a worsening legal and fiscal backdrop.

University of Amsterdam strategic management professor Henk Volberda cautioned that while the Netherlands still ranks well in international business surveys, "there is a disconnect between politics and business".

"I think this government has to rethink the fiscal changes that have been made lately," he said. (Reporting by Charlotte van Campenhout and Toby Sterling; Editing by Kirsten Donovan)