BEIJING — Three Nobel laureates in science and economics who visited North Korea this week for what was billed as an educational exchange said Saturday that they had met university students who were eager to learn, but who were hampered by the North’s tight Internet controls and by rudimentary, decades-old equipment.

Two of the laureates, Aaron J. Ciechanover of Israel, a biologist, and Sir Richard Roberts, the chief scientific officer at New England Biolabs in Massachusetts, said at a news conference in Beijing that they had invited North Korean students to come and work in their laboratories. But that prospect appeared unlikely.

The weeklong visit by Mr. Ciechanover, Mr. Roberts and a third laureate, Finn Erling Kydland, a Norwegian who shared the Nobel for economics in 2004, was organized by the Vienna-based International Peace Foundation and by the National Peace Committee of Korea, an organ of North Korea’s ruling Workers’ Party. The trip, which ended Friday, was authorized by Kim Yong-nam, the president of North Korea’s Supreme People’s Assembly, and was intended as an exchange of educational views, the organizers said.

On Friday, the Workers’ Party opened its first congress in 36 years in Pyongyang, the North Korean capital, but the timing was coincidental, said Uwe Morawetz, the chairman of the International Peace Foundation. He said that the South Korean ambassador in Bangkok had asked that the trip be delayed until after the congress, which is a major propaganda event for North Korea’s top leader, Kim Jong-un, but that the organizers had declined to do so because the visit had been planned long in advance.