* Oct-Dec op profit likely 10.8 trln vs 13.2 trln analyst view
* Revenue likely fell 11 pct to 59 trln
* Estimates come after rival Apple cut sales view on weak China
SEOUL, Jan 8 (Reuters) - South Korea's Samsung Electronics Co Ltd on Tuesday estimated a decline in quarterly operating profit for the first time in two years, as a slowing Chinese economy erodes demand for its chips and handsets.
Weaker earnings at the world's biggest maker of smartphones and semiconductors adds to worries for investors already on edge after Apple Inc last week lowered its quarterly sales forecast, in a rare move, citing poor iPhone sales in China.
Samsung, in a regulatory filing, estimated profit at 10.8 trillion won ($9.67 billion) for October-December last year, down 29 percent from the same period a year earlier. That compared with the 13.2 trillion won average of 26 analyst estimates in a I/B/E/S Refinitiv poll.
It also estimated a 11 percent on-year revenue decline at 59 trillion won.
Samsung will disclose detailed earnings later in January.
Analysts expect Samsung's profit to decline through 2019 as weakness in China persists, Refinitiv data showed.
Prices for DRAM chips, which provide devices with temporary workspaces and allow them to multi-task, declined 10 percent in the fourth quarter, according to industry tracker DRAMeXchange.
Prices of NAND flash memory chips, which hold data permanently, slipped 15 percent.
DRAMeXchange anticipates memory chip prices to fall 10 percent on an average in the first quarter of 2019.
(For an interactive graphic on memory chip prices, click https://tmsnrt.rs/2GYDer8) ($1 = 1,116.4000 won)
(Reporting by Heekyong Yang and Ju-min Park; Editing by Christopher Cushing)