The new revelation comes just a day after PST confirmed that both China and Russia were actively spying within Norwegian borders.
“We have revealed attempts to receive work within our organisation,” Benedicte Bjørnland told Norway's state broadcaster NRK, declining to give any further details.
PST’s Annual Threat Assessment for 2015, released on Wednesday, warned that foreign intelligence services were seeking to plant so-called 'moles' within the organisation.
"Because foreign intelligence services are carrying out intelligence activities against Norwegian interests, they are expected to increasingly attempt to map Norwegian counterintelligence,” the report read. “They are attempting to both recruit our staff and get suitable people to apply for positions with us."
In her interview, Bjørnland refused to rule out the possibility that Russia and China already have agents in key positions in both government and business.
"We should in any case be aware of the possibility of insiders both in the public sector and in other key businesses," she said.
The report named Russia and China as the two countries whose intelligence services mounted a threat to Norway.
“The two states with which Norway has no security policy cooperation and that also have the largest intelligence capacity by far are Russia and China,” the report read. “Of these, we consider Russian intelligence to possess the greatest potential for damaging Norwegian interests.”
Norway is interesting for Russia, the report argued, both because of the country's membership of Nato, and because it shared a border with Russia’s highly militarised Kola peninsular.
“The Russian occupation of the Crimean peninsula and Russia's interference in the political process in Ukraine has also shown that the Russian authorities have the will to use force to achieve their needs,” the report said. “Russia’s intelligence services are looking for information on Norwegian defence, security and preparedness.”