UPDATE 2-Italy's Consob likely to force higher Camfin bid price
* Consob said started procedure to raise bid price
* Lauro 61 bidding to buy out Camfin minority shareholders
* Lauro 61 says to appeal against Consob decision (Adds bidding group to appeal against Consob decision)
MILAN, Sept 12 (Reuters) - Italy's stock market regulator Consob said it has started a procedure that is likely to force bidders for Camfin, the holding that controls tyremaker Pirelli, to increase their bid price.
In a statement on Thursday Consob also said that it is prolonging the end of the offer, which had been scheduled to close on Friday, until Sept. 27. Consob will release its opinion on the offer price before the offer's end, it said.
Lauro 61, led by Pirelli Chairman Marco Tronchetti Provera, has offered 0.80 euros per share to buy out investors in Camfin after acquiring a 12.4 percent stake in the company at the same price from Malacalza Investimenti.
That deal brought to an end years of legal wrangling between Malacalza and Tronchetti Provera, who had been at loggerheads over management issues at the group.
As a result Lauro 61 came to own 61 percent of Camfin and, under Italian rules, had to offer to buy the remaining shares. Malacalza separately bought a 6.98 percent stake in Pirelli.
Market watchdog Consob has been looking at whether a possible agreement among parties involved in the Camfin bid may have resulted in an offer price for the Camfin minority shareholders that was lower than might be deemed fair.
Lauro 61 has said its purchase of Camfin shares and the purchase of Pirelli shares by Malacalza were two totally independent operations, and that it saw no reason why it should change the bid price.
Lauro 61 said it would lodge an appeal against the market watchdog's decision with a regional court.
The investment vehicle is owned by Tronchetti Provera, banks Intesa Sanpaolo and UniCredit, and private equity fund Clessidra.
The bidding group plans to delist Camfin once it gains full control and possibly merge with it.
Camfin shares jumped after Consob's statement, and closed up 8 percent at 0.87 euros. Lauro 61 said it was disappointed that the statement had been released during market hours. (Reporting by Jennifer Clark and Silvia Aloisi; Editing by Anthony Barker and Sonya Hepinstall)