Leeds have named Simon Grayson as their new manager - but Blackpool are considering legal action over the move.
The 39-year-old leaves his post as Seasiders boss to take over the League One side, who sacked Gary McAllister on Sunday after five successive defeats.
Blackpool had refused Leeds permission to speak to the former Aston Villa defender on Monday and turned down a resignation request 24 hours later.
The Championship outfit may now take steps against Grayson and Leeds.
A statement on the Blackpool website read: "Blackpool FC can confirm that Simon Grayson tendered his resignation on Tuesday morning.
"The resignation was not accepted by the board of directors and the club are now considering legal action against both Grayson and Leeds."
The Yorkshireman, who started his career as a Leeds trainee, guided Blackpool to promotion to the Championship in 2007 after two years in charge.
As a player he made two senior appearances for the Elland Road club before joining Leicester City in 1992. A £1.3m move to Villa followed five years later.
"When the opportunity came to come here I couldn't wait to be involved as quickly as possible," Grayson told the Leeds website.
"It's a massive club and close to my heart, having played here before and supporting the club. The size and the ambition is obviously an attraction as well.
"I had a great time at Blackpool. I had a great rapport with the fans and the board. I certainly wouldn't have dropped down a division for any other club and I feel this is the next stage of my managerial career.
"I know there is an expectancy level and it's a challenge I'm looking forward to."
Grayson was installed as favourite for the job on Monday ahead of former Leeds coach Aidy Boothroyd and ex-assistant manager Gus Poyet.
Leeds began looking for their ninth manager in the last 10 years after relieving McAllister of his duties a day after his side lost 3-1 to MK Dons.
That was the Elland Road outfit's seventh defeat in nine matches, a sequence that has resulted in them sliding to ninth place in the table, 15 points adrift of leaders Leicester and 11 off the second automatic promotion slot.
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