TORONTO -- BlackBerry shares have given back a little over half of the spectacular gains that they made late Wednesday after a news report said the Canadian smartphone company had been approached by South Korean rival Samsung with a takeover offer.

Both companies have since issued denials.

Late Wednesday morning, BlackBerry was down $2.51 or 16.7 per cent to $12.51 on the TSX after jumping 30 per cent after the Reuters report was published.

BlackBerry responded late Wednesday that it has not engaged in discussions with Samsung Electronics Co. Ltd. about a possible takeover and Samsung sent an email saying the report was "groundless."

Reuters said Samsung had met with BlackBerry executives over the possibility of buying the Canadian company for as much as US$7.5 billion. The news agency cited both a source familiar with the proposal and related documents.

The two companies are rivals in the smartphone business but have worked together on technology.

BlackBerry and Samsung announced a partnership last November where the Waterloo, Ont.,-based company made its mobile security technology available for the Android operating system that is used in many of Samsung's smartphones.

For BlackBerry, the arrangement gave their software the ability to work on Samsung's Galaxy and Note smartphones, while it provided Samsung an opportunity to get the attention of business customers that BlackBerry courts.

Samsung has been focused on selling its Knox security software to the business community in an effort to compete against similar offerings being developed by Apple Inc. (Nasdaq:AAPL) and others.

"What Samsung needs is credibility in the business space, which is what BlackBerry is pivoting towards at this point," said Carmi Levy, analyst and writer at Voices.com, a London, Ont.-based web technology company.

"There's a lot of complementary benefits for both of these companies to get together."

BlackBerry has been in the crosshairs of interested buyers in the past. Last fall, Chinese company Lenovo was considered a potential bidder though an offer never materialized. Any takeover of BlackBerry would require Canadian government approval and there was speculation that a Lenovo takeover of Canada's premier technology company wouldn't be acceptable.

Chief executive officer John Chen has said he is focused on turning around operations at the company rather than hunting for buyers. Chen was hired in late 2013 after the BlackBerry board conducted an extensive review of strategic options, including discussions with possible buyers for the Waterloo, Ont.-based company.

Traders reacted to the Reuters report by sending BlackBerry's stock to its highest level since early 2012 on the Toronto Stock Exchange. Despite the runup, BlackBerry's current value remains far below the peak when it was the world's leading smartphone company, prior to the emergence of rival products such as the Apple iPhone, Samsung Galaxy and others.

According to the disputed Reuters report, Samsung had proposed a range of US$13.35 to US$15.49 per share in its initial approach to BlackBerry. The offer would be a premium of 38 to 60 per cent over BlackBerry's stock price before the report emerged.