It is thought that the schoolboy striker will be included in the Arsenal U19s squad against Sevilla in the UEFA Youth League on Wednesday.
Obi-Martin recently made his debut for Arsenal U21s against Brighton and is tipped for a bright future at the club.
It will likely be some time until Obi-Martin makes his debut for the Arsenal first-team – but reports that he has trained with the main squad shows just how highly rated he is in north London.
Obi-Martin registered a hat-trick for Arsenal U18s in a 4-0 victory over Southampton in September.
The teenager, who played for England at U16s level, was born in Glostrup, Denmark and has since changed his international alliance.
He has registered seven goals across nine matches for Denmark U17s.
Meanwhile, Arsenal manager Mikel Arteta sent a message to fellow Gunners wonderkid Charlie Patino last week.
The 20-year-old still has a chance of forcing his way into Arteta’s long-term plans following a bright start to his loan spell at Swansea City, the Spaniard insisted.
‘There is always a pathway,’ Arteta said. ‘When we make decisions on those kind of players it is always to keep an eye on them and see if we can evolve the squad in a way. The first thing we do is look at what we have internally.’