MOUNTAIN VIEW, California: Growing delays at U.S. embassies abroad have prompted Google to warn some employees on American visas to reconsider international travel, amid tighter immigration scrutiny under President Donald Trump's administration, Business Insider reported.

According to the report, Google, which Alphabet owns, circulated guidance to certain staff following advice from its external legal counsel, BAL Immigration Law. The internal email, sent on December 18, cautioned employees who require a visa stamp to re-enter the United States not to leave the country because visa processing times have significantly lengthened.

Google did not immediately respond to a request for comment.

Some U.S. embassies and consulates are facing visa appointment backlogs of up to 12 months, the memo said, warning that overseas travel would "risk an extended stay outside the US," according to Business Insider.

The warning comes as the Trump administration steps up immigration enforcement. Earlier this month, the White House announced increased vetting for applicants seeking H-1B visas for highly skilled workers, including enhanced screening of social media accounts.

The H-1B programme, which is widely used by the U.S. technology industry to recruit skilled workers, particularly from India and China, has come under renewed scrutiny. This year, the Trump administration imposed a US$100,000 fee for new H-1B visa applications, further raising the cost of hiring foreign talent.

The latest guidance echoes earlier concerns raised by Alphabet. In September, the company strongly advised employees to avoid international travel and urged H-1B visa holders to remain in the United States, according to an email.