In May 1997, the Swedish Defence Matériel Administration awarded a contract worth around USD25 million to the Czech Republic VOP 026 repair facility for the modification and renovation of 350 ex-East German Army, Russian-built BMP-1 infantry combat vehicles for the Swedish Army.

These upgraded BMP-1 vehicles, designated the Pbv 501 in Swedish Army service, were delivered to Sweden from 1998 through to 2001 to mechanise the Swedish Army infantry brigades.

As of mid-2006, there was no available date for when the Pbv 501 would be phased out of service with the Swedish Army.

A detailed description of the Russian designed BMP-1 is given under the Russian Federation and Associated States. The main differences between the Pbv 502 and the BMP-1 are as follows:

• Removal of the launcher rail for the Koloma KBM 9K11 Malyutka (NATO AT-3 'Sagger') over the 73 mm gun 2A28 and its associated control box inside of the turret

• Weapon monitor circuits include devices inhibiting use of weapons when the hatches are open

• Removal of asbestos elements in certain parts of the vehicle and their replacement by harmless material, while retaining the original functions. This includes brake linings, main clutch lining as well as sealing and insulation

• Installation of a new fire detection and suppression system that does not contain Freon, this can be operated manually or automatically

• External lights, including indicators, now conform to NATO standards

• Sockets for outside starting, preventive charging of batteries and connection of devices are unified in accordance with NATO regulations

• Camouflage system corresponds to NATO regulations

• The accumulator batteries are now stored in a hermetic box ventilated outside of the vehicle space

• Observation devices are fitted with protective covers

• New footsteps, handles and non-slip coverings are installed to ensure safe movement of the crew on the hull

• Holders for Swedish weapons including sub-machine guns, machine guns and ammunition

• Installation of an independent crew heater

• Improved exhaust outlet

• Additional radio installation