The Times is already seeking changes in a six-year contract due to expire in 1993.
He was on a temporary contract due to expire in several weeks, Mr. Klasen said.
Washington is in the final year of his rookie contract, due to earn $535,000 next season.
However, with the 22-year-old's contract due to expire next week, he has agreed terms through to 2020.
FSA may withdraw the offer before approval of the contract due to lack of available funds or other reasons.
Boston also did not want to pay Walker the lucrative contract extension he was seeking, with his contract due to expire after next season.
Jürgen Klopp will instead turn his attention to Juventus's Martin Caceres, who is available on the cheap, with his contract due to run out this summer.
With his contract due to expire next summer, the destiny of the left-footed forward is about to slip out of Nantes' hands.
The three boroughs are currently jointly tendering for a 10-year, £300m-£455m, total facilities management contract due to start in May 2013.
The government hopes to tackle the points raised in time for the next ScotRail passenger services contract, due to come into place at the end of 2014.
Last month the government stripped the company of a recently awarded contract due to fears around weak internal controls and "seriously inadequate" paperwork.
