"There must be the strictest possible system of control over workers' access. Only those with a certificate should be allowed to work," Yury Luzhkov said.
He said the new regulations will apply to workers involved in potentially dangerous activities, including welding.
The explosion occurred at around 7:00 p.m. Moscow time (15:00 GMT) on Friday on the 11th floor of a 22-story building on northwest Moscow's Akademika Korolyova street, blowing out walls and destroying several apartments.
An emergencies ministry spokesman said two women and one man died after being crushed by the collapsed ceiling.
Yevgeny Bobylev also said over 200 people were evacuated from the blast-affected section. Forty-five of them have been given temporary alternative accommodation pending repair work.
Russian Federal Security Service experts have not discovered traces of an explosive device, a law enforcement officer told RIA Novosti.
Speaking at the scene yesterday, Luzhkov said it was unlikely that terrorists caused the explosion, and suggested that welders carelessly using equipment were to blame.
