The 27-year-old, who played for the Pilgrims during a loan spell in 2006, has put pen-to-paper to return ahead of the 2012-2013 season and appeared as a second half substitute in Tuesday's 3-1 friendly win over a Peterborough United XI.

Silk left Grimsby Town earlier in the summer and has previously represented Notts County and Mansfield Town too.

He was on Portsmouth's books when he enjoyed his initial 16-match loan spell with the Pilgrims.