De Mel, who replaced Lalith Kaluperuma as chairman of the selection committee last week, blamed his predecessor for forcing former captain Jayasuriya out of Test cricket.
"The way it was done was absolutely ridiculous," De Mel, a former Test fast bowler, told AFP.
"Sanath has done so much for the country and the selectors should have shown some respect for such a senior player. But they just called him for a meeting and asked him to step down or face the axe."
Jayasuriya, 36, announced during a home series against Pakistan last month he was leaving Test cricket to concentrate on One-day cricket leading up to the World Cup in the Caribbean in March-April next year.
"If a player wants to retire we allow him to announce his retirement before a series," said De Mel. "But this was done in between a series and I don't think Sanath got the respect he deserves."
Kaluperuma said it was a "collective decision" by the previous committee to persuade Jayasuriya to leave Test cricket.
"We felt that Sanath might not get picked for the ongoing tour of England and told him so," said Kaluperuma. "Coach Tom Moody was involved in the discussion as well.
"We thought the World Cup is vital and Sanath is an important member of the One-day team. We wanted to make sure he remained injury-free for the World Cup so we asked him to concentrate on one-dayers only."
De Mel, however, said Jayasuriya was still good enough to play Test cricket.
"I think the selectors got their onions mixed up," he said. "If you get the current crop of players to do a 100-metre sprint, I bet Sanath will come first.
"There's no question about his fitness or commitment."
De Mel hinted he may send Jayasuriya to England if Sri Lanka faltered in the first of three Tests starting at Lord's on Thursday.
"If we don't do all that well in the first Test I might even ask Sanath to consider coming out from retirement and take part in the remainder of the Test series," he said.
"Sanath played a season of county cricket with Somerset last year and he's the only Sri Lankan to have scored a Test double hundred in England. You can't ask for better credentials."
The chief selector also took a swipe at coach Moody, saying the former Australian star had not produced the desired results.
"We were number two in the world rankings when John Dyson was the coach and since Tom Moody took over last year we have slipped to number six," he said.
"I think Moody is more of a strategist. (Batsman) Mahela Jayawardene at times has a problem with his foot movement and Moody hasn't been able to correct it.
"(Fast bowler) Dilhara Fernando has a no-ball problem and instead of helping him, they just drop him and ask him to rectify the problem on his own."