After July 16, non-immigrant US visas held by most non-official foreign workers will no longer be reissued in the United States due to enhanced border security regulations adopted after the September 11, 2001 terrorist attacks in New York and Washington, the department said.

Instead, the affected workers will have to apply for new visas at US embassies and consulates abroad, preferably in their home countries, because domestic facilities do not process visas and are not equipped to handle new immigration procedures, including interviews, it said.

"We recognise that the domestic reissuance of business-related visas to applicants in the United States has been a convenience to the international business community," the department said in a notice published in the Federal Register.

"However, we are discontinuing the reissuance of visas in these categories because of increased interview requirements" and regulations that require new visas to include so-called "biometric indicators" such as fingerprints, it said.

Some 50,000 foreign workers applied to have their visas reissued in the United States last year but the department maintained the new rules would not likely pose significant inconveniences for most people.

For one, the expiration of non-immigrant US visa does not necessarily mean the holder must leave the United States, officials said.

Most foreign workers are allowed to remain in the country, even with an expired non-immigrant visa, for as long as they retain the status under which the visa was initially granted and meet the terms of their admission, they said.

However, if they leave the United States with an expired visa and wish to return, they must apply for a new visa to be re-admitted, the officials said.

"If these persons depart the United States and require new visas to reenter, after July 16 they must seek adjudication of a new visa application at a US embassy or consulate abroad," the department said.

Seven classes of non-immigrant visas -- C, E, H, I, L, O and P -- are covered by the change which will affect skilled and unskilled workers, including computer and information technology experts, journalists, entertainers and athletes.

About 50 percent of these workers are Indian citizens, many of whom work in the technology field, but nationals of some 60 countries also hold visas covered by the new rules, the department said. Britain, China, Japan and South Korea also have significant numbers of citizens with them.