APN Outdoor shares soared on Thursday after France-based outdoor advertising giant JCDecaux made a $1.1 billion offer for the local company late on Wednesday.

Shares in the Australian billboards and outdoor advertising group gained 12.1 per cent to $6.56 on Thursday, their highest level in almost two years.

Responding to the unsolicited offer, APN called JCDecaux’s $6.52 cents a share offer “a modest premium” to recent valuations and said it was assessing the offer.

APN’s board said shareholders should take no action at this stage.

The indicative offer from JCDecaux, the world’s largest outdoor advertising company, represents an 11 per cent premium to the Australian billboard group’s value at the close of trade on the Australian share market on Wednesday.

APN Outdoor owns billboards and advertising on buses, trains and in airports, while JC Decaux has owned capital city street furniture advertising since entering the Australian market in 2000 ahead of the Sydney Olympic Games.

JCDecaux said APN would be a complementary addition to its existing Australian portfolio, which includes a recently won contract for advertising on Melbourne’s Yarra Trams.

APN is yet to respond to the offer, which will be subject to competition and foreign investment reviews.

JCDecaux said its offer does not constitute a formal takeover bid, and rather it wants the APN Outdoor board to enter an agreement under which it will put the proposal to shareholders.

APN Outdoor shares plunged sharply in August, 2016, from around $8.24 following a downgraded earnings outlook and have not recovered since, having traded between $4 and $6 apiece until yesterday’s offer.