This is no surprise to Keegan, who highly rates the only player still at the club from his first spell as manager.
Keegan told the Evening Chronicle, "I am not looking for him to go out, though I'm sure he would come and see me if Liverpool come and knock on his door.
"I know Steve very well - he's got a great sense of humour.
"I'm not surprised if other teams are interested.
"Steve Harper is a very, very good goalkeeper.
"Everyone's always known that, but it's always been hidden by the fact he's not played.
"He's just played his 100th game, but he was here last time I was, which was 1936, so he must be about 50 now!"