BEIJING - North Korea said yesterday that it will begin to allow in more American tourists after years of heavy restrictions on visits to the isolated country, according to a tour operator.

The United States has never had diplomatic relations with North Korea since the Korean War ended in a truce, not a peace treaty. More recently, tensions have remained high over the North’s nuclear program.

Only about 2,000 tourists from the United States have visited since the country opened to Western tourism in 1987, according to the founder of a China-based tour group that says it has taken most of those visitors into the isolated country.

But the Koryo Group, which specializes in North Korea tourism, said it received an e-mail from the state-run Korea International Travel Company yesterday afternoon saying the country will accept more American tourists this year.

The message gave no explanation for the move and said more specific information would come later, the agency’s founder, Nicholas Bonner, said. “This is a big, big change,’’ he said.

Tensions with the outside have risen in recent years over the North’s pursuit of nuclear weapons, with Pyongyang saying this week that it would not resume negotiations aimed at ending such programs until its relations with the United States improve and international sanctions against it are lifted. The United States rejected the proposal.

In recent years, Americans have been allowed to visit North Korea only briefly during the country’s Mass Games, a synchronized propaganda spectacle with a cast of 100,000.

Bonner said his Beijing-based agency escorted about 280 American tourists to the country last year, but estimated those numbers could jump to about 1,000 per year if restrictions were eased.

He said his agency handles about 90 percent of the Americans visiting North Korea.

North Korea is governed by a secretive, hard-line communist regime whose motivations and decision-making processes remain obscure.

The US State Department has no travel warning for North Korea.

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