Nmecha, who on a season’s loan at PNE from Manchester City, is in Germany’s Under-21 squad for two games during the international break.
The 20 year-old has played for England at six age groups from Under-16s through to the Under-21s.
But he has now declared for Germany, the country of his birth and where he lived until the age of nine.
Currently his switch of nationality application is in the hands of FIFA but Nmecha hopes to be involved against France on Thursday and then their friendly with England at Bournemouth next Tuesday.
Joti Chatzialexiou, the sporting director for the Germany FA, said: “Lukas Nmecha declared his interest to play for his country of birth, Germany, to us.
“We would like to support the player with this intention.
“Consequently, we sent an urgent appeal to FIFA regarding a switch in nationality so that he can play for Germany U21s.
“Regardless of whether this decision is approved or not, this international break provides Lukas with the opportunity to get to know his teammates.”
Hamburg-born Nmecha lived in Germany until the age of nine before moving with his family to Manchester.
He joined City’s academy after a few months living in England.
His younger brother Felix, who also plays for City, has played for both Germany and England at youth level.
Nmecha joined North End in August and has played 36 games – 19 starts and 17 from the bench.
He has started the last three games, Alex Neil using him mainly in a wide role rather than as a striker.
Nmecha is one of two PNE first-team players away on international duty.
Sean Maguire is the other, the striker in the Republic of Ireland squad.
After scoring Saturday’s stoppage-time winner against Birmingham, Maguire flew to Dublin on Sunday to meet-up with the Irish.
However, PNE team-mate Alan Browne has had to pull out of the Republic squad.
Browne injured his ankle early in last Wednesday’s win at Middlesbrough and missed the Birmingham game.
North End’s youth-team skipper Adam O’Reilly, who is on loan at Hyde United, has been named in the Republic of Ireland’s Under-18s squad.