Poseidon Containers has secured long-term charters for four containerships with CMA CGM hot on the heels of plans to merge with the French container lines spin-off Global Ship Lease.

The agreement will see the 6,927-teu Mary, Kristina, Katherine and Alexandra (all built 2013) join CMA CGM on contracts worth $135m in core operating profit.

While the Mary has already begun its new contract, the other three ships will not start the new deals until the first half of 2019, a statement says.

The new charters were hailed by Global Ship Lease chief executive Ian Webber as evidence the merger would be a "transformational combination."

"As illustrated by these new charters, the combination will significantly increase our scale and ability to capitalize on favorable fundamentals in the mid-sized and smaller containership segments," he said.

Webber also noted the charter rates were an improvement over their current ones and would contribute to Global Ship Lease's deleveraging.

Last week, George Youroukos-lead Poseidon and Global Ship Lease announced their intention to merge in a $780m deal that will create a 38 ship-strong fleet comprised primarily of smaller and mid-sized vessels.

It will see Poseidon's investors take a nearly 70% stake in the new company.

Global Ship Lease will nominate three members of the new eight-member board to Poseidon's two, but CMA CGM will designate two of those as long as it holds at least a 10%.