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 dipped 0.3% to $13,655.50 a metric ton in official open-outcry ​trading 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 add about 5% this month, the second straight month of gains, largely on ​hopes for a deal to end the Iran war and signs ‌of firmer demand.

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. LME aluminium gained 0.7% in official activity ‌to $3,684.50 a ton, and the premium of the LME cash ⁠contract over the three-month futures climbed to $97 a ton, the highest ​since February 2007, highlighting worries about potential shortages the Iran war is causing in the Gulf, which accounts for about 9% of global output. Among other metals, LME zinc added 0.1% to $3,555 ​and lead rose ‌0.3% to $2,024 while tin and nickel were little changed at $55,100 and $19,100 ⁠respectively.

(Reporting by Eric Onstad; Additional reporting ​by Noel John in Bengaluru; Editing by Jan Harvey and Tomasz Janowski)