LONDON (Reuters) - A lucrative ride on the rollercoaster energy markets helped add to the big increases in profit that BP Plc and Royal Dutch Shell Plc posted yesterday.

BP beat forecasts with a 48 percent leap in first-quarter profit to $6.6 billion, while Shell said earnings rose 12 percent to a record $7.8 billion. BP said a few unusual items flattered its results.

"We had a very good quarter from trading operations," said BP spokesman David Nicholas. "The contribution was something like $400 million above what you would generally see."

BP has a reputation as the industry's top trading firm, an image that dates back to the early 1980s when it led an industry shift to help create the spot oil market — the trading of oil for immediate delivery. Shell, long regarded as more conservative, said it also earned more from trading in the quarter, without giving a precise figure.

"I think we had good trading results," Shell's chief financial officer Peter Voser said on a conference call. "It is up, but it is not in a big way up for us."

Crude oil prices at a record high near $120 a barrel, round-the-clock trading and the appeal of oil to a broader mix of investors highlight the potential for traders to win or lose millions in minutes.

While trading has boosted profit in the last few months, it has also brought BP and Shell under the scrutiny of regulators.

In 2004, Shell's US gas and power trading arm Coral Energy paid $30 million to settle charges it reported fake natural gas trades. Coral did not admit or deny wrongdoing.

BP last year agreed to pay up $303 million to settle charges that it attempted to corner the US propane market in 2004.