STOCKHOLM (Reuters) - Engineering group Alfa Laval reported quarterly earnings and order intake above market expectations on the back of an upturn in the oil and gas sector on Monday and forecast demand would remain at the same level in the second quarter.

The company, a maker of products such as heat exchangers, separators and ballast water treatment equipment, reported order intake of 10.0 billion crowns (844.68 million pounds), above the 9.6 billion seen by analysts.

"Improved activity in upstream oil and gas, on shore, as well as in the off-shore sector contributed to both Energy and Marine reporting a somewhat better order intake than we had expected," it said in a statement.

The Swedish firm said its first-quarter adjusted earnings before interest, taxes and amortization (EBITA) rose to 1.497 billion crowns from a year-ago 1.279 billion, beating a Reuters poll mean forecast for 1.370 billion crowns.

Alfa Laval also said it expected capital expenditure this year to increase somewhat compared to the earlier forecast of 1 billion crowns.

"Due to the strong growth trend in order intake additional investment decisions will be made to ensure capacity and delivery performance in our supply chain," the company said.

Alfa Laval shares were up 3.7 percent by 1101 GMT.

(Reporting by Johannes Hellstrom; editing by Niklas Pollard)