UPDATE 1-Henry Sy son in $940 mln Meralco stake bid

* Henry Sy Jr. offers to buy Lopez family stake in Meralco

* 300 peso/shr offer values deal at $940 mln - source

* PLDT says has first refusal, tag-along rights on stake (Adds PLDT, Lopez comments, background)

By Rosemarie Francisco

MANILA, Oct 30 (Reuters) - A group headed by the son of mall tycoon Henry Sy, one of the Philippines' richest men, made a surprise offer on Friday for a 13.4 percent stake in Manila Electric Co (MER.PS) held by the Lopez business clan and valued at around $940 million.

The offer -- which sources said was at around 300 pesos ($6.32) a share, or a near-60 percent premium -- comes after months of wrangling between PLDT (TEL.PS), the country's most valuable firm, and San Miguel Corp (SMC.PS) (SMCB.PS), its best-known conglomerate, over ownership of Manila Electric (Meralco), the Philippines' leading power retailer.

Henry Sy Jr, eldest son and namesake of the shopping centre magnate, is allied with San Miguel and his entry into the Meralco ownership battle gives the food-to-power group more ammunition against PLDT.

A sale of the Lopez stake to Sy, would give San Miguel control of 56.4 percent of Meralco, leaving PLDT with an around 35 percent stake. The Lopez family, a powerful business clan with power and media interests has run Meralco for decades.

"The plan reflects our confidence in the future prospects of the power sector in general and Meralco in particular. Our offer price represents a fair market value for such assets," Sy, president of Triratna Holdings Corp, said in a statement.

The Lopez group said it would discuss the proposal at a board meeting on Thursday.

Sy's statement did not give the offer price, but two sources, who asked not to be named as they were not authorised to discuss the issue publicly, said it was around 300 pesos a share, which would value the entire 13.4 percent Lopez stake in Meralco at 44.75 billion pesos ($940 million).

PLDT Chairman Manuel Pangilinan told Reuters: "We have the right of first refusal (over the Lopez stake) ... and tag-along rights as well."

Under those tag-along rights, PLDT can sell its holdings under the same terms and conditions applying to the Lopez stake.

Sy's offer came just days after the Lopez family and Pangilinan separately disclosed they were in talks for PLDT to buy half the Lopez stake in Meralco. [ID:nMAN498722] [ID:nMNA002433]

Meralco shares have more than trebled this year amid the drawn-out battle for ownership. [ID:nMAN439653]

The Lopez family sold a 20 percent chunk of Meralco to a PLDT unit in March for $414 million. ($1=47.6 pesos) (Editing by Ian Geoghegan)