* Costs fell 5 pct, capex by 20 pct in 2014 - PwC
* PwC still sees long-term growth from China
By Zandi Shabalala
JOHANNESBURG, June 4 (Reuters) - The world's top 40 mining firms cut costs by a combined 5 percent and capital spending by 20 percent last year as they grappled with a plunge in prices that drove their market value to a 10-year low, a report showed on Thursday.
Auditing firm PricewaterhouseCoopers' (PwC) annual survey, which looks at the world's largest 40 miners by market capitalisation, showed the combined equity value of the companies dropped by $156 billion last year to $791 billion.
That was the second straight year of decline and left the combined market value about half what it was four years ago.
Despite this, PwC said dividend yields rose to an all-time high of 5 percent as miners preferred to compensate shareholders rather than reinvest cash in their businesses.
Nickel, zinc and platinum were the only commodities that generated higher revenues for mining firms compared with the previous year, while there were falls in bulk commodities such as coal, iron ore and copper.
Despite the challenges, PwC said demand for copper and other metals was likely to rise over the longer-term from the world's top consumer, China.
"We believe that the reforms being undertaken will place China in a good position to continue to grow over the long term, albeit at a slower pace," the report said.
The survey, titled "The Gloves are Off", includes firms such as Goldcorp Inc, Glencore, Shandong Gold Mining and Anglo American.
For the first time, no South African-based companies featured in the list, with Impala Platinum falling out of the top-40 group after featuring in 2013. (Editing by James Macharia and Mark Potter)