They include Kazakhstan's Ilya Ilyin, a four-time world champion who also won gold in the 94kg category at the Beijing Games in 2008.
The others are Kazakhstan trio Zulfiya Chinshanlo (53kg), Maiya Maneza (63kg) and Svetlana Podobedova (75kg).
If all four are disqualified, Kazakhstan would drop from 12th to 23rd in the 2012 medal standings.
Six other lifters who competed at the 2012 Games also tested positive after hundreds of samples were reanalysed.
Among them are Russia's Apti Aukhadov, who won silver at 85kgs, Ukraine's Yuliya Kalina, who took bronze at 58kgs, and Belarusian Marina Shkermankova, who won bronze at 69kgs.
Completing the group of doping positives are Azerbaijan's Boyanka Kostova and Belarus duo Dzina Sazanavets and Yauheni Zharnasek.
Four London 2012 Olympic weightlifting champions have tested positive for performance-enhancing drugs.