Magellan Midstream Partners LP said Thursday that its board approved the increase of its quarterly cash distribution to 94.25 cents, crediting better-than-expected cash flow.

The news sent the partnership’s units up more than 5 percent to a new all-time high in afternoon trading.

The Tulsa, Okla.-based oil distributor’s new distribution represents a 12 percent increase over its previous distribution of 84 cents and a 20 percent increase over its year-ago level of 78.5 cents.

Magellan said it had planned to increase its annual distribution by about 9 percent this year, but its cash flow has been better than expected. As a result, the partnership said its targeting distributions for the full year 2012 that are 18 percent higher than 2011 levels.

It also set a goal of increasing the distributions an additional 10 percent in 2013, as new projects come on line.

The second-quarter distribution will be paid Aug. 14 to unit holders of record as of Aug. 7, the partnership said.

Magellan units rose $4.08, or 5.5 percent, to $78.05 in afternoon trading, after peaking at $78.24 earlier in the day and passing their previous 52-week high of $77.15.

Magellan’s units have risen steadily over the past two years, increasing their value by about 52 percent.