The Colombian striker, 28, has been heavily linked with Arsenal in recent weeks and it is believed that he could be soon on his way to the Emirates Stadium.
Jackson's agent has confirmed his client will depart Porto for £25.5million but stopped short of naming the club who the free-scoring attacker will join this summer.
"Jackson's future is already pretty much decided," Luiz Henrique Pompano told O Jogo.
"Things should be clarified in the next few days. He'll go to a big European club, which will be announced as soon as the contract is signed.
"From what's been agreed, Porto will receive the €35m (£25.5m) from the release clause."Negotiations have been underway for a few weeks, there are still some details to be sorted out, and then Jackson Martinez's departure from Porto can become a reality."
Jackson, who scored a whopping 92 goals in just three season with Porto, is also a reported target for Manchester United.