LONDON -- This week saw concerns over Chinese and U.S. economic performance flare up once again. U.S. jobs data for June disappointed, while a surprise decision to cut lending rates in China suggested that the administration there is concerned about how quickly growth is slowing. Despite this, oil and gas prices rose slightly through the week, with the United States Oil Fund (NYSE: USO) finishing ahead 3.75% and the United States Natural Gas Fund (NYSE: UNG) outperforming its oil-based cousin to gain more than 5% for the week.

However, rising oil and gas prices weren't enough to protect some London-traded oil and gas companies, whose share prices plunged dramatically. Here are three of this week's worst performers.

Aurelian Oil & Gas (LSE: AUL.L)
Aurelian Oil & Gas fell 22% to 11 pence this week following an uninspiring and inconclusive operational update that prompted a major sell-off. The Eastern European explorer confirmed that it is continuing to examine its strategic options and left investors uncertain about its future prospects.

Max Petroleum (LSE: MXP.L)
Max Petroleum dived 18% this week to 3.15 pence, compounding a crashing loss endured during June. This week's bad news was that Kazakhstan-focused Max suspended operations at its NUR-1 deep well due to a lack of sufficient funds to overcome technical problems. Although the financial situation now looks grim, Max emphasized that its shallow wells are continuing to generate positive cash flow, and further funding options are being discussed with its bank.

Bahamas Petroleum (LSE: BPC.L)
Bahamas Petroleum slid more than 10% to 8.2 pence this week, proving that no news isn't always good news. Although the company did not release any fresh information, concerns persist over the prospects for the company's Bahamas licenses following the country's May elections.

As always, smaller oil and gas shares can be volatile, and this week's losers could be next week's winners. To learn more about the potential of oil and gas shares to deliver outstanding multibagging gains, you can download this free Fool report: "Ten Steps To Making A Million In The Market." It's a great starting point for anyone who is serious about outperforming the wider market by a large margin and building up a million-pound portfolio.

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