(Adds analyst comment and dateline, updates prices)

By Eric Onstad

LONDON, May 29 (Reuters) - Copper prices edged lower on

Friday as investors waited for more news about a potential deal

to extend a ceasefire in Iran and as the dollar firmed.

Three-month copper on the London Metal Exchange was

down 0.1% at $13,690 a metric ton by 0910 GMT after gaining 1.3%

in the previous session.

LME copper rebounded on Thursday on the back of news that

the U.S. and Iran reached an agreement to extend their ceasefire

and lift restrictions on shipping through the Strait of Hormuz.

But President Donald Trump has yet to approve it and Iranian

state media said it had not been finalized.

"Copper is drifting lower today, it seems like we've got

some profit-taking. We've certainly had a small uptrend for the

last two weeks, but it's stalling a bit," said Ole Hansen, head

of commodity strategy at Saxo Bank in Copenhagen.

LME copper is on track to gain 5.3% this month, largely on

hopes for a deal to end the Iran war and signs of firmer demand.

The most-traded copper contract on the Shanghai

Futures Exchange added 0.8% to 104,840 yuan a ton. The contract

has gained about 3% so far this month.

Both contracts were up for the second straight month.

"A successful deal could open the door for stronger gains,

while any breakdown risks reigniting inflationary pressures and

capping upside," said Tim Waterer, chief market analyst at KCM

Trade.

Copper was also supported by the continued flow of metal to

the U.S. as traders took advantage of a slight premium of U.S.

futures over those in London.

U.S. Comex copper futures dipped 0.2% to $6.44 a lb,

bringing the premium of Comex over LME copper to 3.7% or $511 a

ton.

"If you take copper out of the market into the U.S. then

that helps to tighten the overall global market, so it's

difficult not to paint a picture of underpinned and supported

prices going forward," Hansen said.

Among other metals, LME aluminium was little changed

at $3,660 a ton, zinc added 0.3% to $3,563, lead

rose 0.3% to $2,024, tin gained 0.4% to $55,300, and

nickel dipped 0.1% to $19,090.