BP Capital Markets PLC, the funding arm of U.K. energy giant BP PLC (BP), is preparing to sell 5- and 10-year bonds Tuesday in a benchmark offering that people familiar with the sale say will likely reach $3 billion.

The bonds will likely price in the low to mid 200 basis points over comparable Treasury securities, these investors add, noting that the tranches will be split roughly equally.

Leading the sale are Barclays Capital, BNP Paribas, Citigroup, Mizuho Securities USA Inc., and Royal Bank of Scotland. A call to a BP spokesman wasn't immediately returned.

The bonds will be guaranteed by the parent company and are expected to be rated A2 by Moody's Investors Service and A by Standard & Poor's. Proceeds will used for general corporate purposes such as repaying existing borrowings, according to a company prospectus filed with the Securities and Exchange Commission.

BP Capital Market's last U.S. bond was in August 2009, when it sold $2 billion in notes with coupons of 1.55% for two-year debt and 3.875% for 5.6-year debt, according to Dealogic data. Deutsche Bank, Morgan Stanley, BNP and RBS ran that sale.