Burnley striker Agyei scored five times in 21 appearances during his spell at the Banks’s Stadium, while Bury winger Ismail managed three goals in 24 games after both players joined the club at the end of August.
Manager Jon Whitney told the club’s official website: “We would like to thank both Zeli and Dan for their efforts.
“Dan’s attitude has been really good but we’ve just decided to go in a different direction and we couldn’t guarantee him minutes here.
“We would have absolutely loved to have kept Zeli but unfortunately he’s Bury’s player, so they have called him back.”
England manager Gareth Southgate has claimed that the country needs to boot racism out of its own football before criticising World Cup hosts Russia.
Newcastle have been linked with a shock move for former Sunderland goalkeeper Simon Mignolet during the summer.