In a statement Sanchez accused Barnet of a "lack of loyalty" and of "losing their nerve".
He said: "Following the termination of my contract by Barnet FC, I'd like to express my extreme disappointment at the lack of loyalty shown in me by the club.
Watch highlights of Sanchez's last game in charge of Barnet in the 1-1 draw against Hereford (UK only)
"It is the same lack of loyalty the club accused Martin Allen of showing when he walked out on Barnet towards the end of last season.
"When I took over from Martin, the club were three points adrift of safety with just four games of the season left and under serious threat of relegation to the Conference.
"However, thanks to a fantastic effort from the players, staff and myself, Barnet took seven points from those last four games and avoided relegation.
"Now, exactly a year since my appointment, the club are three points clear off the relegation zone with three games to go.
"I certainly felt that recent performances would see the club remain clear of the threat of relegation.
"Unfortunately, that confidence seems not to have been mirrored in the boardroom and I am disappointed the club have lost their nerve at such a vital stage of the season."
SANCHEZ'S RECORD AT BARNET
Played - 53
Won - 15
Drew - 12
Lost - 26
Allen, who has had two previous spells in charge at Underhill, began his managerial career at Barnet in March 2003, when they were in the Conference, and left a year later to join Brentford, before having spells with MK Dons, Leicester and Cheltenham.
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