Oman's Renaissance Services aims to raise about $500 million in a London listing of its Dubai-based oilfield services unit and may also divest part of its stake in a secondary offer, it said on Sunday.   

Renaissance's Topaz Energy and Marine stake is expected to be above 51 percent after the IPO, it said in its 2010 annual report. The exact size of the secondary share sale will be decided closer to the date of Topaz's IPO pricing.

Renaissance did not provide a specific timeline for the IPO but said valuations for the share sale will be through a book building process.   

A source close to the deal said on Thursday that the offering is expected to be completed in early April and is being run by Bank of America Merrill Lynch and JP Morgan.

"Renaissance now believes a listing of Topaz on the London Stock Exchange offers the most effective way to optimise future growth opportunities and increase shareholder value," chairman Samir Fancy said in the report.   

Renaissance bought Topaz in 2005. Last year, the firm had revenues of $408 million and profits of $70 million, Renaissance said in the report.

In December, Renaissance acquired Abu Dhabi-based Al Wasita Emirates for Services and Catering in a 56 million dirhams ($15.25 million) deal to expand its contract services operations in the UAE.  - Reuters