Williams and Oakes are the first out of the Liberty Stadium door

The pair, among eight players out of contract at the end of the season, have not been offered new deals.

Goalkeeper Oakes, who joined on a free transfer last summer, has played just one League One game since Martinez took charge in February.

Defender or midfielder Williams has struggled with injury this season, but is attracting interest for other clubs.

The Cyprus international joined for an undisclosed fee from Gillingham last January, and played in 10 of the 12 games under Martinez.

"It's not exactly the nicest part of the job, but it has to be done,'' Martinez told the club's website. "It's part of football.

"I'd like to thank both players for their efforts. I know Tom already has other options, while the timing of my appointment was not ideal from Andy's point of view.

"While I've only seen him in one League game, I know he's more than a capable goalkeeper, but it's an area we need to freshen up.''

Swansea said that negotiations with the six remaining out of contract players - Kevin Austin, Kristian O'Leary, Izzy Iriekpen, Adebayo Akinfenwa, Steve Watt and Garry Monk - will continue over the next few weeks.

Martinez has offered senior contracts to youth team pair 18-year-old defender Kyle Graves and 16-year-old striker Kerry Morgan.