The Mali International Mining and Conference and Exhibition, known as JMP Mali 2015, began on 17 November and finished yesterday at the International Conference Centre in Bamako.
Concerns have been raised that some of those attending or organising the event may have been among the 170 people thought to have been taken hostage after gunmen attacked the Radisson Blu hotel in the early hours of this morning.
Mali special forces stormed the building in an effort to free the hostages and bring the situation under control.
AME Trade, which organised the event, said in a statement that it believed most of the delegates had already left Bamako but that it was working to clarify the situation.
"We are aware that a majority of our clients and delegates left on flights departing Bamako from 18 November," the statement said.
"As the situation is very fluid and ongoing, it is impossible to make any categorical statements as to whom or where the hostages are.
"Obviously, AME Trade is concerned about the safety of our staff and clients and are in constant touch with the local authorities and are standing by to offer any sort of assistance that we can to those who may have been affected in some way by the unfolding unfortunate incident.
"We can also confirm that one senior team member of the company is currently in Bamako, but is safe and not in close proximity with the locations currently under attack."
The company said it would provide additional information "as the picture becomes clearer".
On the event website, JMP Mali is billed as the "must-attend show to do successful business in the Malian mining sector" and is said to be "the only event organised with the full support from the government of Mali".