Pakistan has expressed "disappointment" at Washington's decision to include its nationals in the National Security Entry-Exit Registration System, which requires them to register with the US government.

US ambassador to Pakistan, Nancy Powell was summoned to meet Foreign Minister Khurshid Muhammad Kasuri and.

A foreign ministry spokesman said, "The minister conveyed Pakistan's deep sense of disappointment and concern over the inclusion of the country in the list prepared by the US Immigration and Naturalisation Service."

Kasuri said that the new measures are "excessive and unnecessary as far as Pakistani nationals are concerned," he added.

The inclusion has created "unprecedented difficulties" for those living in and visiting the US, he said.

The move brings over 100,000 US-based Pakistanis under direct monitoring by the police.

Early this month the US justice department had added Pakistan and Saudi Arabia to the list of countries, whose citizens are subject to additional scrutiny when they enter the US.

The list also includes Afghanistan, Algeria, Bahrain, Eritrea, Iran, Iraq, Lebanon, Libya, Morocco, North Korea, Oman, Qatar, Somalia, Sudan, Syria, Tunisia, the United Arab Emirates, and Yemen.

More reports from Pakistan