"We are still in contact with Swansea and we are nearing an agreement," said Oosterveer.
De Vries himself as also expressed a desire to stay at The Liberty Stadium: "I think the chairman (Huw Jenkins) has made a good step by appointing Paulo Sousa as the new manager.
"It's up to the chairman and my agent to get things sorted and hopefully it will be in a positive way.
"Pre-season training starts on Monday and I think the chairman wants it to get sorted before then.
"Everything can be really quick if things go well and let's hope they do."