* U.S. crude inventories expected to fall for 6th week
* Prices pressured as IMF lowers global growth forecasts
* GRAPHIC: Iran seizes tanker tmsnrt.rs/2O646ZX (New throughout, updates prices, market activity and comments, adds Reuters poll on U.S. crude inventories)
By Collin Eaton
HOUSTON, July 23 (Reuters) - Oil prices were largely flat around $63 a barrel on Tuesday as expectations of lower U.S. crude supplies were offset by weaker demand forecasts and the full restart of Libya's largest oil field.
Brent crude rose 9 cents to $63.35 a barrel by 12:28 p.m. CDT (1728 GMT). U.S. West Texas Intermediate crude was up 21 cents at $56.43.
U.S. crude oil stockpiles likely fell for a sixth consecutive week, dropping by 4 million barrels, an extended Reuters poll showed on Tuesday.
"We're oversupplied big here in the United States, and the global demand situation is not all that good," said Robert Yawger, director of energy futures at Mizuho in New York.
In the week ended July 12, U.S. commercial crude stocks were 455.9 million barrels, almost 45 million barrels above levels this time last year, according to U.S. government data.
On Tuesday, the International Monetary Fund (IMF) cut its forecast for global growth, warning that further U.S.-China tariffs or a disorderly exit for Britain from the European union could weaken investment and disrupt supply chains.
"It was a reminder of what the oil market is staring down, with demand contracting," said John Kilduff, a partner at Again Capital LLC in New York. "That’s what's been holding back prices."
On Sunday, Goldman Sachs lowered its 2019 oil demand projection, joining other forecasters.
The International Energy Agency said global supply remains plentiful due to strong growth in output from the United States and other non-OPEC producers.
Oil may find more support if forecasts are correct for another drop in U.S. crude inventories. The American Petroleum Institute, an industry group, releases its inventory report Tuesday at 4:30 p.m. EDT (2030 GMT). The U.S. government's official figures are due Wednesday morning.
The full restart of Libya's largest oil field also pressured prices, which had rallied a day earlier on concerns of supply disruptions in the heavily trafficked Strait of Hormuz, following Iran's capture of a British oil tanker.
Middle East tensions have periodically bolstered prices as the United States has aimed to cut off Iran's oil exports. Also adding support have been supply cuts led by the Organization of the Petroleum Exporting Countries.
"The situation with Iran seems contained for now, and Libya's full supply is coming back," said Bill Baruch, president at Blue Line Futures LLC in Chicago. (Additional reporting by Alex Lawler, Koustav Samanta; Editing by Susan Fenton and David Gregorio)