WASHINGTON—Obama administration officials are raising alarms about a scientific-cooperation pact between North Korea and Iran that officials said could advance the nuclear and missile programs of both countries.

The agreement, reached in September, bears a close resemblance to one North Korea signed with Syria in 2002, U.S. and United Nations officials said, just as Pyongyang began secretly constructing a plutonium-producing nuclear reactor in eastern Syria. "They have pretty much the same wording," said Olli Heinonen, a former lead weapons inspector at the U.N. nuclear watchdog agency.

The U.S. is paying new attention to the pact after recent North Korean nuclear and missile tests, at a time when Tehran has come closer to producing enough enriched nuclear fuel for a bomb, U.S. officials said. Washington is concerned that the two military allies will seek to use the agreement to advance their nuclear capabilities, just as they have jointly developed missile systems, according to U.S. and U.N. officials.

"Any 'scientific cooperation' between Iran and North Korea is potentially a source of real concern to us, and we'll have to follow it closely," said a senior U.S. official on Friday.

This year, Pyongyang conducted its third nuclear-weapons test, and for the first time successfully launched a long-range missile into space. Iran hasn't developed an atomic bomb, and says it has no nuclear-weapons program, despite U.S. accusations to the contrary.