In a heated newspaper column in the UK, Fletcher said claims that England cheated by using substitute fielders were "poppycock", and that Ponting's outburst in the fourth Test at Trent Bridge was because he knew Australia was about to lose the Ashes battle.
The Zimbabwe-born coach also stated his Australia counterpart John Buchanan had "a rant" at him over the subject.
In more serious allegations, Fletcher accused Ponting and vice-captain Adam Gilchrist of repeatedly confronting umpires with "overbearing body language" and unnamed teammates of verbally abusing a groundsman at Trent Bridge.
The bad blood first emerged between Ponting and Fletcher during the Trent Bridge Test, when the Australia captain swore at the England coach, who was standing on a dressing room balcony.
An irate Ponting had just been run out by gun sub fielder Gary Pratt, who came on as a substitute for injured bowler Simon Jones.
Fletcher denied provoking the outburst. "I glanced down at Ponting. He was still ranting and raving. I did not want to be drawn into any sort of conflict, so I smiled. It only incensed him more. He completely blew his top," Fletcher wrote.
"Looking back now, that might have been the moment when it became clear England (was) going to win the Ashes.
"This was an Australia side under enormous pressure. (It was) grasping any opportunity, however ludicrous, to hit back at us."
Fletcher rejected England's use of substitute fielders as being underhand, and disputed Ponting's claim that the tactics were unsporting.
"What riled me most about Ponting's comments was his reference to the spirit of the game," Fletcher wrote.
The England coach said Australia flouted the spirit of cricket throughout the Ashes series. Fletcher queried the legitimacy of a back injury to Michael Clarke in the third Test at Old Trafford that forced him out for a day when Australia was in the field.
"When he appeared to bat in the second innings, did he have a runner? No. Did he suddenly recover that morning?" Fletcher said.
"Second - and this is the most serious example - did you notice how Ponting would invariably walk straight up to an umpire and challenge his decision using overbearing body language?
"On occasions he was supported by Adam Gilchrist. Sometimes there was even a third person involved.
Is that really what we want kids to see when they watch cricket? Is that in the spirit of the game?"
England recently won the spirit of cricket award at the International Cricket Council's annual awards dinner in Sydney.
Fletcher further accused Australia of confronting Trent Bridge groundsman Steve Birks over comments he had made, saying his wicket wouldn't take spin.
"We had it on good authority that the groundsman was verbally abused by some of those Australia players," Fletcher said.
"This petulant behaviour was no doubt the upshot of comments made by the groundsman before the Test."
Fletcher's long list of pent-up gripes also included Gilchrist shouting, "We're owed one dodgy decision here boys" near umpires, and Simon Jones being fined after he gave Australia opening batsman Matt Hayden a send off.
But Ponting also copped a further spray for his decision to bowl first after winning the toss at Edgbaston, when England scored 407 on the first day.
"It was a complete shock. What was he thinking?" Fletcher wrote. "He must have been duped by all that talk of a damp pitch."
Australia coach John Buchanan last night declined to respond to Fletcher's comments.