Earlier Friday in London trading, shares of BP (BP) gained on rumors the largest oil company in the world, Exxon Mobil (XOM), is considering a bid for the oil company responsible for the largest oil spill in the U.S., Reuters reported.

According to Reuters, by 2:29 p.m. GMT, BP shares were up 1.1% in London. Of course, the companies declined to comment, and in U.S. trading, shares had retreated by nearly 1% as of 1:20 p.m. EST.

This is not the first time such a rumor has been floated. In July, DailyFinance reported on similar speculations. The Sunday Times of London then reported that Exxon Mobil had approached regulators in Washington for approval to buy BP. According to the Daily Mail at the time, "the U.S. government has told Exxon that it will not stand in its way if it chooses to attempt a takeover."

While BP has been selling assets in an attempt to raise up to $30 billion by the end of 2011 and pay for the ever mounting cleanup costs and compensation for victims of the disaster, the chances of Exxon making an offer for BP are probably just as remote today as they were four months ago.