JLIF, one of Britain's biggest listed investors in public infrastructure projects, said earlier this month it was in talks with a consortium of funds, including Dalmore Capital and Equitix Investment Management, about the potential offer at 142.5 pence per share.

The offer includes a payment of a dividend of up to 3.57 pence per share to JLIF shareholders.

The concerned investors include the fund's second largest shareholder, Baillie Gifford, the source added.

Baillie Gifford has a 6.4 percent stake in JLIF, according to Thomson Reuters Eikon.

Under British takeover rules, the consortium has until Aug. 13 to either announce a firm intention to make an offer or walk away.

JLIF's shares closed at 140.4 pence on Monday.

Sky News reported the news earlier on Monday.

($1 = 0.7611 pounds)

(Reporting by Carolyn Cohn; Editing by Adrian Croft)