Morrell, who started all four games and impressed for his country at Euro 2020, is part of Rob Page's 27-man squad selected for next month's World Cup qualifying matches against Finland, Belarus and Estonia.
Wales kick-off the latest international break with a trip to face Finland on September 1 before fixtures in Estonia (September 5) and a home meeting with Estonia (September 8).
It means midfielder Morrell - handed his Blues debut in the 0-0 draw at Doncaster on Saturday - will be unavailable for the trip to face AFC Wimbledon in the Papa John's Trophy on September 7.
The Blues will hope to have Morrell back in contention for the League One trip to MK Dons on September 11.
Pompey's Republic of Ireland internationals, goalkeeper Gavin Bazunu and Ronan Curtis, are also likely to receive call-ups when the Eire squad is named.