CEO Hunter Harrison of CP answers shareholders questions during the company's annual general meeting in Calgary, Alberta, May 14, 2015. REUTERS/Todd Korol

MONTREAL (Reuters) - The outgoing chief executive of Canadian Pacific Railway Ltd CP.TO, said to be in advanced talks with a partner to shake up CSX Corp CSX.O, cannot hire any CP management except its chief of staff, according to details of an agreement published on Monday.

Hunter Harrison “cannot solicit or hire the company’s employees above the level of manager,” apart from chief of staff Mark Wallace, during a 36-month period, the separation agreement said.

Canadian Pacific last week announced Harrison’s early departure from the railway company he led after activist fund Pershing Square tossed out the previous CEO in a 2012 proxy fight.

Harrison and former Pershing Square partner Paul Hilal are said by a source to be teaming up to invest in CSX, with Harrison playing a similar leadership role to improve the company’s performance as he did at Canadian Pacific.

Under the agreement filed on Monday, Harrison would be forbidden from working for CP rivals Canadian National Railway Co CNR.TO , BNSF Railway Co [BNISF.UL] and Union Pacific Railway Co.

CSX stock soared 20 percent following news of the plan.