Duffy, 27, was part of New Zealand's enlarged squad for their ongoing Test series against England but was trimmed from the initial 20-man group ahead of the first Test at Lord's, having played in both warm-up games.

"We're delighted to be able to secure Jacob's services for our next two Championship matches," Paul Downton, Kent's director of cricket, said. "It's a very busy part of the season with Championship matches intermingled with the Vitality Blast and Jacob will strengthen our seam attack at this crucial stage of our Championship campaign."

Duffy will be Kent's second overseas player for the Championship alongside the South African allrounder George Linde, who is available across formats. Qais Ahmad, the Afghan legspinner, is at the club for the T20 Blast but is not expected to play in the Championship.

Kent have endured a difficult start to the season and are ninth in the 10-team top division of the Championship, with four draws and two losses from their six games so far. They have also struggled in the Blast despite their status as defending champions, finally picking up their first win in their sixth group game against Middlesex on Sunday.