Makeshift memorial set up in tribute to Wagner chief Prigozhin in Saint Petersburg

A crowd gathers in front of the "PMC Wagner Centre" in Saint Petersburg to pay tribute to Yevgeny Prigozhin, head of the Wagner mercenary group.

According to Russian officials, Prigozhin was on board a plane that crashed north-west of the capital Moscow on August 23, leaving no survivors -- the crash comes two months after he launched a short-lived rebellion against President Vladimir Putin.