UPDATE 3-Total's sweetened Synenco bid gains support

(Adds analyst comment, details on project ownership, share prices)

OTTAWA, July 24 (Reuters) - Total SA (TOTF.PA) increased its takeover bid for oil sands start-up Synenco Energy Inc SYN.TO by 14 percent, the companies said on Thursday, helping secure additional shareholder support.

The new offer of C$10.25 a share in cash, raises the value of the deal to about C$530.5 million ($525 million), and represents a 39 percent premium to the 30-day average share price for the period ended April 25, the firms said.

Total, which is looking to boost its holdings in Canada's vast oil sands region, said it has now signed lock-up agreements with D.E. Shaw Laminar Portfolios and Wellington Management Co LLP, which combined control about 23 percent of Synenco common shares. Those shares had not been tendered to the previous offer.

Earlier this month it was reported that those shareholders had rejected Total's April 28 bid of C$9 a share and were holding out for a richer offer.

Shares in Synenco jumped nearly 14 percent to C$10.20 on the Toronto Stock Exchange on Thursday morning, while Total stock dipped 2.6 percent to 47.77 euros in Paris.

The takeover "looks like a done deal" said Genuity Capital Markets analyst Philip Skolnick. Support from the two large shareholders in addition to the 58 percent of shares previously tendered to the deal exceeds Total's 66 percent approval requirement.

There is little likelihood of a competing bid, Skolnick added.

"Because: one) Synenco admitted in May, 2007 that the Northern Lights project has very skinny economics; two) its partner, China-based Sinopec, may be perceived as an undesirable partner to many; and, three) Synenco has only one phase of growth," he said in a note.

French oil major Total expects its revised bid to remain open until Aug. 5.

The oil sands region of northern Alberta is the world's largest storehouse of oil outside the Middle East. Total already operates the planned $9 billion Joslyn oil sands project and has a stake in the Surmont steam-driven development.

Calgary, Alberta-based Synenco, which operates the proposed Northern Lights oil sands project in northern Alberta, said its board of directors recommends shareholders accept the new offer.

Synenco put itself on the block last year after the Northern Lights project's cost estimate nearly doubled to C$10.7 billion.

Synenco has a 60 percent interest in the project, which could have daily output of 114,5000 barrels of bitumen, the tar-like crude stripped from the sands.

Sinopec (600028.SS) holds the remaining stake in Northern Lights, which still requires regulatory approval before it can go ahead.

($1=$1.01 Canadian) (Reporting by Susan Taylor; editing by Rob Wilson)