Arsenal announced the deal on Friday, with Akpom moving abroad again after spending part of last season on loan in Belgium.
Arsenal defender Sokratis Papastathopoulos and AEK Athens players have pledged to donate blood and give money in support of those affected.
Greece's oldest football club Panathinaikos have been banned from European competition for three seasons for failing to pay their debts.
Panathinaikos say long-delayed payments have been made to Michael Essien and two others in hopes of avoiding losing nine points in the Greek league.
The Greek Superleague have deducted three points from Panathinaikos after the club failed to settle unpaid wages with former player Jens Wemmer.
Olympiakos owner Evangelos Marinakis has fined his players €400,000 and ordered some of them to go on holiday until the end of the season.
Greek Superleague disciplinary committee has also docked the club three points and fined them €63,000.
Greece has lifted its suspension of football after saying it received a commitment from clubs to reform rules aimed at combating violence.
Evangelos Marinakis was cleared by the Supreme Court but could still face a charge of bribery relating to match manipulation, reports in Greece said.
Olympiakos and Nottingham Forest owner Vangelis Marinakis says drug-trafficking charges against him are part of a Greek government-led "conspiracy" to
Herbert Huebel said a series of incidents, culminating in a gun-toting club owner running onto the pitch, were "unacceptable."
PAOK president Ivan Savvidis has apologised for storming the pitch during Sunday's clash with AEK Athens while appearing to carry a gun.
Greece's sports minister says Greek Super League matches have been suspended indefinitely after the gun-toting owner of PAOK marched onto the pitch.
A disputed goal in a Greek league match on Sunday between AEK and PAOK led to a pitch invasion by one of the team owners, who appeared to have a gun.
About 3,000 PAOK supporters marched peacefully through Thessaloniki on Thursday to protest against the Greek club's punishment for fan violence.
A Greek sports court has deducted three points from title contenders PAOK for match violence.
Brisbane defender Avraam Papadopoulos has been handed a suspended two-and-a-half year jail sentence by a Greek court for illegally betting on matches.
Olympiakos coach Oscar Garcia was hit by an object thrown from the crowd ahead of a Greek Superleague game between PAOK Salonika and Olympiakos.
Olympiakos are planning an appeal after the Greek champions were docked three points by a court on Monday following fan violence.
UEFA say Panathinaikos face a one-season ban from European competition if they fail to pay creditors this month.
Olympiakos have re-signed Kevin Mirallas from Everton on loan until the end of the season, the clubs confirmed on Sunday.
Kevin Mirallas is set to return to Olympiakos after the Greek club announced a deal has been agreed with Everton.
Arsenal have completed the signing of 20-year-old Greek defender Konstantinos Mavropanos from PAS Giannina.
Arsene Wenger has confirmed that Arsenal will make 20-year-old Greek defender Konstantinos Mavropanos their first January signing from PAS Giannina.
Arsenal are in talks to sign Greek defender Konstantinos Mavropanos from PAS Giannina, a club source has told ESPN FC.