Brighton & Hove Albion duo midfielder Oliver Norwood and winger Jiri Skalak are both wanted by the Tigers along with Scunthorpe United’s Conor Townsend.
“We need more players and that is what we are actively endeavouring to do,” said Adkins, whose side lost 1-0 at Rochdale over the weekend.
“We have had bids on the table that have now come out publicly. Three players and those deals have not been done. Those offers we put in have been rejected. The club obviously has to be in a position to decide to continue those discussions or not.
“We will just have to wait and see. We are actively looking to bring players in, which is important.”
Former Huddersfield Town midfielder Norwood has played under Adkins before at Reading, while Skalak is wanted to bring some competition out wide.
Townsend, like Norwood and Skalak in the last 12 months of his contract, is wanted to boost a defence that will be without Ondrej Mazuch for the first two months of the season due to a knee injury.
Adkins added: “We are trying to get that balance of 20 outfield players with the Under-23s to supplement that. You could see against Rochdale that we are still short on numbers.”
Only goalkeeper George Long of City’s six signings did not feature at Spotland.