Security has been stepped up on the Moscow rapid transit system ahead of the anniversary of the March 29, 2010, twin suicide bombings in which 40 people died.
A police spokesman said there has been increased police and security presence on the subway.
Police have been warned of a possible terror attack by two Islamist female suicide bombers on Tuesday and have their Photofits.
Chechen warlord Doku Umarov claimed responsibility for the suicide bombings on two Moscow subway stations on March 29 last year. He is also said to have ordered a deadly bomb attack on Moscow's Domodedovo International Airport in January of this year that claimed 37 lives.
MOSCOW, March 28 (RIA Novosti)
