The two sides have been in discussions over a deal for the Iceland international for some weeks, although reports in recent days have suggested that the talks have stalled as the parties haggle over a transfer fee of between £40m and £50m.
Swans boss Paul Clement today confirmed that he has left Sigurdsson out of his squad for their Premier League opener this weekend amid the uncertainty, and in his own news conference Koeman was keen to point out that the deal remains on track.
"It is still close, that has not changed," he told reporters. "I heard rumours that the talks broke down, but we are still in negotiations with Swansea.
"Of course everybody would like news on that, it is better for us and them, but it is always a game between the buying and selling club and it is close, let's hope we get an agreement soon.
"We are not in a hurry but we hope to do a deal."
Sigurdsson was instrumental in Swansea's Premier League survival last term, contributing nine goals and 13 assists in what was an underwhelming campaign for the Welsh side.