May 7 (Reuters) - French construction-to-telecoms group Bouygues on Tuesday reported first-quarter core earnings below expectations, citing a sharp decline in its real estate unit Immobilier that overshadowed good performance from its energy arm Equans.

"Bouygues Immobilier will continue to face a challenging market environment, with low visibility on the timetable for recovery," the company said in a press release.

In early April, Bouygues said it planned to lay off over 20% of staff in its real estate unit in France as the construction market weakens.

The family-owned group posted quarterly current operating profit from activities (COPA) of 26 million euros ($28 million).

This compares to 34 million euros expected by analysts in a company-compiled consensus, with estimates ranging from a loss of 17 million to a profit of 59 million.

Bouygues also confirmed its financial outlook announced in late February.

($1 = 0.9289 euros) (Reporting by Michal Aleksandrowicz in Gdansk; Editing by Tom Hogue and Subhranshu Sahu)