Talks between the Gunners and their two star players, who are out of contract at the end of next season, are said to have hit a snag in recent weeks.
Wenger recently claimed that he requires 'a good bank' to fulfil the duo's wage demands but, with other clubs potentially looking to swoop in next year, the Frenchman is still unsure whether they will commit.
"It was always difficult. What has changed is the numbers but it was always difficult to keep the good players because they are wanted by other clubs," he told reporters.
"Players want to get the maximum as they only have 10 years playing at the top level."
Ozil is Arsenal's highest earner with a weekly salary of £140,000, while Sanchez takes home £130,000 a week.