Harmison is playing two games for Highveld Lions

Harmison was playing for South African team Highveld Lions and took nine wickets in the match.

England have named their squad for the tour of Sri Lanka but have left the door open for Harmison if he can prove his form and fitness.

Gibson has been monitoring his progress in South Africa and said: "He bowled quite well and in pretty good areas."

England head to Sri Lanka on Thursday for a three-Test series starting on 1 December.

Harmison has not played for England since June because of a hernia injury but his form was wayward last season.

His infamous wide at the start of last winter's Ashes, which was caught by Andrew Flintoff at slip, is now legendary in cricket circles.

"I'm feeding information all the time to the selectors on how he's going, his mindset and the wickets," said Gibson.

"But the ultimate decision isn't mine, so they have that decision to make."

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But figures of 6-91 and 3-78 against Cape Cobras on a slow wicket in Paarl suggest the signs are good for a return to the England fold.

"First day, first innings, it was his first ball since July, so you expected probably that he wasn't going to go in at 100%," said Gibson.

"He's here to sort of get back into things and he was obvious a little bit rusty for a start.

"The second innings was a lot better, a lot more control and he's obviously had a lot more bowling under his belt and it showed.

In the past, Harmison has struggled with the pressures of being away from home on tour, and Gibson said this could also be a factor in deciding whether or not he would be picked to play.

"As he's happy in himself that he's bowling well then obviously he's going to move on to Sri Lanka," he said.

"I don't think he would want to go to Sri Lanka if he didn't feel like he was ready for that.

"He's an experienced cricketer and he knows what will be required of him when he goes to Sri Lanka. He knows where he is now in relation to where he needs to be and whether he is not there yet.

"But he's still got another game next Thursday and the way he's bowled in the second innings gives him a lot more confidence going into that game next week."