NEW YORK: A group of chief executive officers (CEOs) at the largest US companies expressed serious concern about the Trump administration's immigration policy and said the rules increase uncertainty and undermine economic growth.In the letter signed by 59 CEOs including Tim Cook of Apple Inc, JPMorgan Chase & Co's Jamie Dimon and Doug Parker of American Airlines, the executives said that many of their employees were now facing uncertainty due to issues such as 'inconsistent immigration decisions' that would likely curtail work permits for spouses of skilled immigrants ."As the federal government undertakes its legitimate review of immigration rules, it must avoid making changes that disrupt the lives of thousands of law-abiding and skilled employees, and that inflict substantial harm on US competitiveness," the CEOs said in a letter dated Wednesday.The executives faulted US Citizenship and Immigration Services ( USCIS ), which is under Nielsen's authority, for having inconsistent determinations that can result in sudden denials to employees who have been successfully permitted for years.In other cases, the department has revoked work permits to spouses of legal immigrant workers. In some cases, these problems affect employees permitted under at the H-1B program, which lets firms hire skilled foreign recruits to fill specialised positions."Out of fairness to these employees -- and to avoid unnecessary costs and complications for American businesses -- the US government should not change the rules in the middle of the process," the letter said.Indian IT companies, which are among the major beneficiaries of H-1B visas , has a significant number of its employees deployed at third-party worksites. A significant number of American banking, travel and commercial services depend on on-site IT workers from India to get their job done.The CEOs are a part of the Business Roundtable, which is a lobbying group and is currently chaired by Dimon. While Business Roundtable has been discussing immigration policy for years, the letter was prompted by specific recent regulatory actions taken by US Citizenship and Immigration Services, which is soon expected to revoke work authorization eligibility for spouses."Together, the USCIS actions significantly increase the likelihood that a long-term employee-who has followed the rules and who has been authorized by the US government multiple times to work in the United States-will lose his or her status," the letter said."At a time when the number of job vacancies are reaching historic highs due to labor shortages, now is not the time restrict access to talent," the letter added.The government should not change the rules in the middle of the process as it could result in unnecessary costs and complications, the executives said in a letter to the Homeland Security Secretary Kirstjen Nielsen.Nielsen, a Trump appointee, told reporters at a White House briefing on Thursday that the administration was only strictly enforcing the law."This administration did not create a policy of separating families ... What has changed is that we no longer exempt entire classes of people who break the law," she said.