Arsenal and Chelsea target Jackson Martinez has renegotiated his contract with Porto, reducing his release clause to £28m.

Both clubs have been tracking the Colombian, but were unwilling to meet the previous buy-out figure, which HITC Sport reports as being over £30m.

The new clause will not be active until the next summer, however, as Porto also announced they had extended their player's contract to run up until 2017.

"In the agreement we signed, we decided on three more years of contract and determined that the release fee won't take effect for this current transfer window or for the January one," Porto president Pinto da Costa is quoted as saying.

Porto had previously wanted to up his contract to just under £50 million, but Martinez and his agent reportedly believed it would end his chances of moving on.