Adds details on the joint venture

July 1 (Reuters) - British warehouse landlord Segro SGRO.L said on Wednesday it would form a 50-50 joint venture with an international investor to develop and operate three UK logistics parks along the M1 motorway corridor, with a fully developed gross asset value of about £3 billion ($3.97 billion).

Here are some details:

• Segro will seed the joint venture with three logistics parks in Radlett, Coventry and Northampton, selling each for about £1 billion.

• The deal comes shortly after U.S. logistics firm Prologis PLD.N made public its £12.6 billion takeover proposal for Segro, following the UK-based real estate investment trust's rejection of the initial approach earlier in June.

• The parks currently comprise 225,000 square metres of fully leased space generating £25 million in headline rent, plus 380 acres of developable land. The M1 Motorway corridor connects the three locations to London.

• When fully developed and let, the sites are expected to deliver about 925,000 square metres of warehouse space and £135 million in headline rent, with development is expected to be completed by 2030.

• Funding for development is expected to come from a combination of partner equity and third-party debt at the joint venture level.

($1 = 0.7550 pounds)