Some conduit bodies are approved for splices. space and wire count is very limited. The body has to have a cubic inch capacity marked on it. There are no specific rules in the CEC that say no but there are none that say yes either. The trick here is, some bodies are approved for splices and many inspectors will respect the Approved use with some evidence suplied from the wholsale and installer.
According the Alberta Standata Code you can't. The code does not permit "conduit fittings" to be used as a junction box. However, in Alberta we have interpreted the term "equivalent device" in rule 12-3000(1) to include "conduit fittings" in special applications (i.e. connection to solenoids, photocells, etc) Wire leads from these devices must be integral to the device. Where the device has a bonding conductor and the conduit fitting has no provisions for attaching a bonding conductor, a separate bonding conductor must be provided in the conduit system to the fitting. The fitting must also comply with the requirements of rule 12-3034 and table 22.
I would look at 12-910, and if the fitting is part of the raceway where conductors continue through then I would say no splices because the fitting is part of the raceway. But if the conduit stops at the LB, then you may have a case for splicing with sufficient space as per Mikesh's post.