SYDNEY (Reuters) - Shares of Australian shopping mall giant Westfield Corp (>> Westfield Corp Ltd) rose as much as 15 percent on Wednesday, their biggest single-day gain, after the company said it would accept a $16 billion takeover offer from France's Unibail-Rodamco SE (>> Unibail-Rodamco).

The shares hit a high of A$9.77 after coming out of a trading halt at 0000 GMT before easing to A$9.73, up 14.5 percent, while the broader market was up 0.1 percent.

That was below Unibail-Rodamco's offer of A$10.01, reflecting risks that Australia's biggest company takeover on record may encounter regulatory challenges.

Shares of Scentre Group (>> Sacgasco Ltd), which Westfield spun off in 2014 to hold its Australian shopping centers while Westfield kept the U.S. and British assets, were up 1.1 percent, on top of the previous day's 4 percent rally amid speculation about the Westfield deal.

The private companies of Westfield Chairman Frank Lowy own about 5 percent of Scentre, according to Thomson Reuters data.

In French trading overnight, shares of Unibail-Rodamco fell 4 percent with analysts at Kepler Cheuvreux saying the deal looked expensive.

($1 = 1.3229 Australian dollars)

(Reporting by Byron Kaye; Editing by Stephen Coates)

Stocks treated in this article : Unibail-Rodamco, Scentre Group, Westfield Corp Ltd, Sacgasco Ltd