It emerged this week that Koeman was planning to return to former employers Feyenoord for both defenders at the end of this season.
Feyenoord are aware of the growing interest in their defensive duo and Voetbal International says they intend to secure Kongolo and Van Beek to new contracts in the coming weeks.
For Kongolo, a deal through to 2020 is being drawn up, while Van Beek will be offered a one-year extension to his current contract, which runs to 2016.
"Two years ago I still not yet proved myself and I had no contract," recalled Van Beek. "Now suddenly it goes very quickly. I'm also very happy at Feyenoord."
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