By Nicole Jao and Shariq Khan

(Reuters) -BP has delayed the restart of a crude distillation unit and a coker at its 435,000 barrel-per-day Whiting, Indiana, refinery from maintenance, boosting fuel prices in the Chicago market, industry sources said on Tuesday.

BP, which started the planned turnaround at the largest refinery in the U.S. Midwest in late September, began restarting units involved in the turnaround in early November. The restart had been scheduled for mid-November.

A source said at least two of the units - the 250,000-bpd sour crude distillation unit and the 102,000-bpd coker unit - experienced issues during the restart process. The units are expected to be back online this week, the source added.

Traders told Reuters that they had to find other sources of gasoline and diesel in the past few days.

Chicago-market CBOB gasoline traded half a cent per gallon below futures benchmark on the New York Mercantile Exchange on Tuesday, traders said, compared with a 14-cent discount in the previous session.

Chicago ultra-low sulfur diesel traded at a four-cent discount to futures, compared with a 15-cent discount previously.

BP did not immediately respond to inquiries about the units experiencing issues during startup.

It had issued an alert on Monday about flaring at the Whiting refinery. "Flares are an essential safety device that helps the refinery safely manage excess gases during periods of maintenance or operational disruptions," the company said in a statement.

The flaring concluded on Monday, a BP spokesperson said.

In February, BP shut the refinery for roughly a month due to a plantwide power outage.

(Reporting by Nicole Jao and Shariq Khan in New York; Editing by David Gregorio, Bill Berkrot and Marguerita Choy)