MOSCOW, July 27 (RIA Novosti) - The number of Russians who have contracted the A/H1N1 virus has risen to 18, Russia's sanitary watchdog said on Monday.

"By July 26 the number of laboratory confirmed cases of infection rose to 18," Rospotrebnadzor said in a press release.

All the patients diagnosed with swine flu in Russia had recently returned from vacations or business trips abroad, mainly from Spain.

The World Health Organization (WHO) has confirmed 154,985 officially registered swine flu cases including 917 deaths in 135 countries and territories worldwide.

Rospotrebnadzor is continuing with checks on the condition of airline passengers who arrive from countries with confirmed cases of swine flu.

Since the beginning of monitoring Rospotrebnadzor has examined 8,073 flights, 660,439 passengers and 55,915 crew members.