* Aveva does not give reasons for end of talks
* Schneider Electric declined to comment
* Aveva shares slump as much as 20.1 pct (Adds source on reason talks ended, more analyst reaction)
By Noor Zainab Hussain
June 15 (Reuters) - Aveva Group Plc said on Wednesday talks over a possible tie up with France's Schneider Electric SE had ended, sending the British software maker's shares down as much as 20 percent.
Aveva said on Monday it had received a revised, conditional proposal from Schneider Electric, six months after the French company pulled out of a deal to buy a majority of the company.
The companies have since been in talks over the merits of the proposed deal, that would have be a reverse takeover under UK listing rules.
Schneider Electric declined to comment on the end of the talks on Wednesday. Aveva declined to give a reason for the breakdown in discussions.
A source close to the talks said the hurdles that derailed the deal in December, such as the complexity of integrating the two operations, still loomed large in the new proposal.
Aveva, founded in 1967 as a spin-off from Cambridge University, had agreed to a deal in July under which Schneider was to pay 550 million pounds ($779 million) for new shares in the British company.
But the companies called off the transaction in December, saying the combination would have been too risky due to the complex structure of the deal.
JP Morgan analyst Stacy Pollard said of the collapse in talks on Wednesday: "If we had to guess, we would say Schneider lowered the price between July and December of last year, and then Schneider came back this week with a similar price thinking it would look relatively better now that Aveva's financial forecasts have been reduced by 9-15 percent."
Analyst George O'Connor at Panmure Gordon, meanwhile, said he had hoped Schneider would have sweetened the deal in order to move it along faster than the last time, when the French company had been considered slow.
Aveva shares closed down 12 percent at 1,628 pence. Schneider Electric closed up 2.1 percent at 53.84 euros.
Aveva, which makes software used to design oil rigs, ships and nuclear power stations, reported in May an 18 percent drop in full-year profit, reflecting tough conditions for its customers in South America and South Korea.
It gets 40 percent of its revenue from oil and gas markets, where companies have cut spending sharply.
"They are now holding something that looks a bit wounded from a structural standpoint ... potential trade buyers will just want to see some progress in terms of how Aveva grinds it out through these difficult times," O'Connor said.
($1 = 0.7058 pounds)
$1 = 0.8910 euros Additional reporting by Paul Sandle in London; Editing by Sunil Nair, Anupama Dwivedi and Mark Potter