MOSCOW (Reuters) - Switzerland said on Saturday that Swiss fighter jets that flew alongside a Russian government airliner heading to Peru had merely been making routine checks, after Moscow demanded an explanation.

A Reuters reporter on board saw Swiss F/A-18 jets approach the plane, carrying a Russian delegation on Friday to an Asia-Pacific summit, and escort it while it was in Swiss airspace.

"(We) have expressed surprise and asked for explanations from Switzerland," Russia's embassy in Switzerland tweeted on Saturday.

The Swiss Defense Ministry said two of its F/A-18s had flown alongside the Russian plane for seven minutes over Swiss territory.

It said such checks were conducted around 400 times a year to double-check the identity of planes belonging to foreign governments.

"It's like police patrols in the street checking a car to make sure it wasn't stolen," a spokesman said.

Russian President Vladimir Putin flew to the summit of the Asia-Pacific Economic Cooperation forum (APEC) on a different aircraft.

(Reporting by Denis Pinchuk and Maria Kiselyova, Shadia Nasralla in Vienna; writing by Maria Kiselyova; Editing by Stephen Powell)