* COMEX copper stocks at highest since 2004
* Traders diverted shipments to U.S. after China bought more scrap
* Solid contango, tepid U.S. demand suggests stocks to rise further
MELBOURNE, July 17 (Reuters) - COMEX copper stockpiles in the United States are set to rise from their current 13-year highs because China is buying more scrap metal and as anticipated infrastructure spending by the Trump Administration is yet to appear.
The expected inventory growth highlights the lackluster demand for the metal, used primarily in white goods and for power transmission, and should cap prices through 2017. The U.S. is the world's second-biggest copper user after China.
COMEX copper stockpiles have climbed to 166,000 short tons as of July 11, equivalent to about 183,000 metric tonnes, the most since May 2004, and an increase of 88 percent since the end of 2016, data from the exchange showed.
With the COMEX copper futures contracts in a contango, the market structure when prompt prices are less than those for later delivery, traders have an incentive to store more of the metal, especially as U.S. demand remains soft. <:0#HG CHT>
"Weve had the build up but we have not yet had the run down, which means that demand hasn't come yet," said Dane Davis, metals analyst for Barclays Capital in New York.
"(Traders are)not moving that metal elsewhere. They are paying the interest and fees on it, in anticipation, that when the economy starts to come in stronger in maybe 2018 or 2019, that copper will be used up."
The front-month COMEX copper contract climbed 11 percent by mid-February to a one-year high above $2.77 a pound, than but has since eased back to around $2.70.
U.S. President Donald Trump came into office promising to improve the country's infrastructure. His election also raised expectations for an improved business climate that would spur copper demand along with the construction spending.
"There was this belief that with Trump coming into power, youd see massive infrastructure deployment, taxes would be cut, the economy would be reinvigorated, and youd have this very pro-growth policy and with that, the U.S. would be consuming more copper," said Barclay's Davis.
"So people were building up the inventories in anticipation of future demand in the U.S."
Expectations that the U.S. would slap a duty on imports from Mexico, a major U.S. copper supplier, also attracted imports, two copper traders said.
U.S. copper imports grew by 26 percent to 314,235 tonnes in the first five months of the year from 2016, data from the World Bureau of Metal Statistics showed. Most of the increase was due to an 83 percent surge in imports from Chile.
Chile is the biggest exporter of copper to China. However, China has boosted its imports of lower-priced copper scrap this year, part of a flood of scrap into global markets as prices climbed in February. That caused traders to divert Chinese shipments elsewhere.
"(Copper) demand in the first quarter was weak globally as scrap was at record discounts and eagerly picked up by fabricators, (so) consumers and traders stuck with excess cathode delivered to both COMEX and LME," said a source at a commodity hedge fund in New York.
"Tonnages sold to China on term contracts for 2017 was weak, some of that tonnage, mainly South American origin, made its way to COMEX."
(Reporting by Melanie Burton; Editing by Christian Schmollinger)