MILAN, May 10 (Reuters) - Shares in Italy's Saipem slumped 7% on Tuesday as uncertainty over the global economic outlook cast a shadow over the energy services group's plans to raise capital.

Saipem said in March it would launch a 2 billion euro ($2.1 billion) cash call this year as part of a turnaround plan, after warning in January it would report a 2021 loss of over one-third of the company's equity.

Chief Executive Francesco Caio told Il Sole 24 Ore daily on Tuesday that Saipem was looking to bring forward the capital hike and launch it in the summer.

Bestinver analyst Marco Opipari said given market volatility and risks to the global economic outlook there could be no certainty Saipem would be able to clinch the deal by the third quarter.

"This is not a very favorable time for markets," Opipari said.

At 1143 GMT, Saipem shares were down 6.9%, underperforming the European oil and gas stocks, which was down 0.9%.

Saipem's rescue plan, which envisions scaling back the group's green ambitions to focus on more traditional oil and gas business, will include asset sales worth over 1.5 billion euros.

Chief Operating Officer Alessandro Puliti told Il Sole 24 Ore, in the same interview as Caio, the group expected to sign a deal to sell its onshore drilling business by the end of May.

He has previously said the sale could be worth over 500 million euros.

Puliti, who joined Saipem in February to represent key investor Eni, said he did not expect "any other surprises" after a thorough review of the company's backlog.

The shock profit warning in January was prompted by a significant deterioration of margins on some contracts including offshore wind.

Saipem, controlled by Eni and state lender CDP, had been looking to develop new lines of business to meet an increasing customer focus on green technologies. ($1 = 0.9477 euros) (Reporting by Federico Maccioni Additional reporting by Giancarlo Navach Editing by Agnieszka Flak and Mark Potter)