* Guanabara increases offer to 90 pence from 77 pence
* Says received acceptances representing about 25.5 percent
* EcoSecurities recommends shareholders take no action
* Shares in EcoSecurities rise 6.7 percent (Adds EcoSecurities response, analysts, Tricorona no comment)
LONDON, Sept 1 (Reuters) - Carbon offset company EcoSecurities is mulling an increased cash takeover offer valuing it at about 106 million pounds ($173 million) from co-founder and former president Pedro Moura Costa.
Costa's Guanabara Holdings increased its cash offer for EcoSecurities to 90 pence a share from 77 pence on Tuesday, and extended the deadline for the bid until Sept. 18.
It also lowered the level of acceptances needed for the bid to become successful to 50 percent from 80 percent and said it had received acceptances representing about 25.5 percent of EcoSecurities' shares for its offer.
For EcoSecurities chairman Mark Nicholls, the hostile takeover bid is no doubt reminscient of the one staged by British Gas Owner Centrica for Venture Production.
Nicholls was deputy chairman of the oil and gas producer until Centrica secured control of over 50 percent of Venture's shares last week.
EcoSecurities responded late on Tuesday to the increased Guanabara offer by recommending shareholders take no action.
"The board of EcoSecurities is considering the terms of the revised offer and awaits the publication of the revised offer document by Guanabara," it said in a statement.
Guanabara said there would be no further increases in its offer, which represents a premium of about 98 percent on EcoSecurities' share price on June 4 before the initial bid announcement, and there would be no further extensions to the acceptance period.
Analysts were divided on whether the revised bid would be successful.
"The combination of an increased offer still in cash, plus a softening of acceptance terms makes it more likely to succeed," said Andrew Shepherd-Barron at KBC Peel Hunt, who has a fair value of 80 pence on the shares.
Gus Hochschild at Mirabaud described the price as "woefully short" and said he still expected Swedish company Tricorona to make a bid.
"This might be partly in cash and paper, and for any bid to garner a sufficient amount of interest it must be above the 100p mark," he said.
Tricorona, which said in July it was mulling a bid for EcoSecurities, declined to comment on Tuesday.
Shares in EcoSecurities, which develops carbon offsetting projects under the Kyoto Protocol's Clean Development Mechanism scheme, rose 6.7 percent on Tuesday to close at 88 pence. (Reporting by Victoria Bryan and Michael Szabo; Additional reporting by Paul Sandle; Editing by Rupert Winchester ) ($1=.6126 Pound)