Oil prices gained on Monday in early Asian trading hours after the US intercepted a Venezuelan oil tanker over the weekend.
The US is also pursuing another tanker, officials told Reuters on Sunday, in what would be the third such operation in less than two weeks if it succeeds.
US West Texas Intermediate crude was up 34 cents, or 0.6 per cent, at $56.86 per barrel as of GMT 2323.
Brent futures rose 65 cents, or 1.1 per cent, to settle at $60.47 per barrel, while US West Texas Intermediate (WTI) crude rose 51 cents, or 0.9 per cent, to settle at $56.66.
That put Brent and WTI down about 1 per cent this week after both crude benchmarks fell about 4 per cent last week.
In other energy markets, a recent drop in US gasoline futures to a four-year low cut 321- and gasoline crack spreads, which measure refining profit margins, to their lowest since February.
