UPDATE 2-USW sees both Sunoco contracts agreed by end week

(Adds union comment on document review continuing through Wednesday, paragraph 5)

HOUSTON, March 3 (Reuters) - Talks between the United Steelworkers union and top Northeast U.S. refiner Sunoco Inc (SUN.N) are expected to yield tentative contract agreements by the end of the week for workers at the company's two Pennsylvania refineries, a USW spokeswoman said on Tuesday.

"We will see both agreements by the end of the week," said the USW's Lynne Baker.

A tentative contract agreement was reached Monday for the company's 335,000-barrel-per-day (bpd) Philadelphia refinery -- Sunoco's largest -- while contract talks continue on Tuesday at the 178,000 bpd Marcus Hook refinery.

A Sunoco spokesman said the company was optimistic about the Marcus Hook talks.

The USW said on its website Tuesday evening that document review will continue through Wednesday and details on meetings and a vote will be released when the tentative agreement is signed.

"We're optimistic that we can reach an agreement sometime soon," said Sunoco spokesman Thomas Golembeski.

Neither side would provide details about Monday's agreement at the Philadelphia refinery, beyond Sunoco saying the contract would not allow involuntary layoffs but would give the company room to offer voluntary severance packages.

Workers at both plants came near walking off their jobs on Sunday as the union and Sunoco deadlocked over the company's desire to reduce employment by 15 percent at the two refineries.