The Swedish parliament has held its first war game in 20 years in response to worries over global politics as tensions with Russia rise.

Speaker Urban Ahlin said on Tuesday a delegation of 50 legislators - which would have the power to replace parliament in the event of the threat of war or an outright conflict - held the drill on Monday at an unknown location.

He declined to give details on what the manoeuvre involved.

"These are secret scenarios ... You were exposed to pressure," Ahlin told AFP news agency. "It went really well."

The delegation is made up of politicians from the left-wing, centre-right and far-right parties.

A non-NATO member, Sweden has not seen armed conflict on its territory in two centuries.

Rising hostility

The drill had been planned since 2014, but Ahlin said an increasingly hostile situation in the world and in the region also prompted the exercise.

"The worsened [global] environment also has a significance," he said, adding the drill would have been postponed if Sweden deemed the world and region safe.

The last time lawmakers held such an exercise was in 1997.

"If everything had been great, then people would have said we can wait for a few more years," Ahlin said.

"Unfortunately, we see a direction in which countries are boosting their weaponry," he said, without naming any countries.

READ MORE: Is Russia really a threat to the Baltic states?

Sweden this month announced plans to bring back conscription this year - seven years after abandoning it - to respond to global security challenges, including Russia's assertive behaviour in the Baltic Sea region.

"We are in a context where Russia has annexed Crimea," said Swedish Minister of Defence Peter Hultqvist at the time of the announcement.

"They are doing more exercises in our immediate vicinity," he said.

The Swedish military budget has been slashed over the past two decades as its mission was revamped to focus more on peacekeeping operations abroad and less on domestic defence.

Russia has repeatedly warned Sweden and neighbouring Finland against joining NATO, an issue regularly debated in both countries.