The Wall Street Journal's news website Marketwatch.com has claimed that several companies may be considering making bids for FTSE 100-listed mining giant Rio Tinto's stake in its Canadian unit.Marketwatch claimed that the Canadian iron ore operations of Rio Tinto, Iron Ore Company of Canada, had been put on the block earlier this year, citing unnamed "people familiar with the matter" as its source of information. The news agency claimed that Glencore Xstrata and private equity firm Blackstone Group could be among possible the suitors circling it and said that analysts had estimated Rio's 59% interest in Iron Ore Company of Canada could be worth around $4.0bn, valuing the entire business at around $7.0bn. However, despite its preliminary interest, MarketWatch.com said that, according to "one person familiar with the matter", there was a good chance Glencore Xstrata wouldn't buy the stake. The news agency pointed out that the mining and commodities trading group was still in the process of integrating Glencore and Xstrata, the two firms that merged this year to create the London-listed company.Again citing "people familiar with the matter", the news website claimed that other potential bidders to have shown an interest in the stake included India's Hindalco Industries and London Stock Exchange-listed Vedanta Resources When Digital Look contacted Rio Tinto's London press office, a spokesperson said the group would make no comment on the subject. Rio Tinto's global iron ore shipments were up 7.0% to 57.3mt compared to the corresponding period in 2012 and global iron ore production was up 4.0% over the same time frame, according to its first quarter results. The group reported that first-quarter saleable production at Iron Ore Company of Canada was 20% higher than the same period of 2012. The group's share price was up 1.44% to 2,898p at 12:16 on Monday following a day high of 2,902p per share.