(Reuters) - Mexico's Pemex, the world's most indebted energy company, plans to restructure parts of its business in an attempt to save costs, a May document seen by Reuters showed on Thursday.

Earlier reports, citing another document from last month suggesting it could include a layoff of over 3,000 tenured employees and save up to around 10.5 billion pesos ($543.40 million), were neither confirmed nor denied in the updated version.

The May document did, however, confirm that Angel Cid Munguia was taking over as head of the company's exploration and production arm, following the surprise departure of Nestor Martinez.

Reuters reviewed both documents but two sources had told the news agency that the plan had significantly changed since April.

Pemex did not respond to a request for comment.

($1 = 19.3228 Mexican pesos)