@Html.ActionLink("Edit Agent", "AgentEdit", "BankListMasterController",
new { agentId = int.Parse(item.AgentId), id = item.ID}, null)
That should do the trick
And rationale is: as per http://msdn.microsoft.com/en-us/library/system.web.mvc.html.linkextensions.actionlink(v=vs.108).aspx
You won't find there method with (HtmlHelper, string, string, string, object) there's however (HtmlHelper, string, string, string, object, object) where the second last object is route values and the last are html attributes.