(Adds analyst comment, updates prices, changes dateline)

LONDON, March 20 (Reuters) - London copper prices hit a

five-month high on Thursday breaking above a major psychological

mark of $10,000 per metric ton before retreating under pressure

from a stronger dollar.

Benchmark three-month copper CMCU3 on the London Metal

Exchange (LME) fell 0.1% to $9,975 a ton by 1151 GMT after

hitting $10,046.50, its highest since October 3.

Supporting the London price is the continuing growth in the

most active May copper futures on the U.S. Comex exchange

, which were last up 0.5% at $5.125 a pound after hitting

a ten-month high of $5.1485.

The premium of the Comex most active contract hit a record

high of $1,342 per ton on Wednesday and was last at $1,319 as

the United States continues a probe into potential new tariffs

on copper. U.S. President Donald Trump's 25% tariffs on steel

and aluminium products took effect last week.

With a wide premium between the Comex and LME copper and the

tariff threat itself, lots of copper is heading to the United

States now, a source at a U.S. warehouse operator said.

The anticipated surge in imports into the U.S. is tightening

supplies in other regions, analysts at ING said in a note.

Comex copper stocks are down 7.5% since

mid-February to 93,154 tons, but outflows from the LME copper

stocks continue, daily LME data showed. The copper stocks in the

LME-registered warehouses are at 223,275 metric

tons, their lowest since mid-July.

LME aluminium rose 0.5% to $2,682.50 a ton and zinc

gained 0.1% to $2,926.50 after daily LME data showed

massive fresh cancellations, bringing the cancelled stocks to

60% of the total for both metals.

The cancellations indicate only the intention to remove the

product from the LME system, and the metal can be put back on

warrant.

LME lead fell 1.0% to $2,065.50, tin lost

0.3% to $34,815 and nickel was down 0.3% at $16,355.