Four Czechoslovakian diplomats and the head of the state airline have been expelled from Sweden for spying.

A security police report accused them today of gathering military information and conducting industrial espionage, especially in the field of high technology. Swedish state television reported today that the new JAS fighter plane project was a target.

A Swedish Foreign Ministry statement issued today said the Czechoslovaks' activity had not caused Sweden any damage but "could have done so had it been allowed to continue."

It said the national police board had informed the Swedish government of the intelligence activities at the end of April.

The statement said the five were engaged in activities "incompatible with their official mandate here."

It said an investigation into the matter did not reveal any third country involvement. However, an afternoon daily newspaper, Expressen, quoting unnamed sources, said the five had received instructions from the Soviets.

Expressen reported that the security police had the embassy under surveillance for two years. The newspaper said the operation was discovered when the Czechoslovaks tried to recruit Swedish security police as agents.

The newspaper identified the four diplomats as first secretary Jan Kroupa, 42; military attache Jan Sovjak, 35; trade attache Ludvig Vanhara, 42; press attache Lubomir Kopaj, 30; and Pavel Scherzl, 33, manager of the Czechoslovakian state airline, CSA.