Using extra & with XMLPoke of nAnt

When using XMLPoke on nAnt I used extra amp; when String already contains &

For example

<xmlpoke file="Menu.xml" xpath="//Item[Name[text()='ams']]//ArgumentExpression" value="https://www.myserver.com/Home.aspx?TID={session}&amp;cid={cid}&amp;Username={username}&amp;uiculture={uiculture}" />

I used following extra &amp; as shown below and XMLPoke worked.

<xmlpoke file="Menu.xml" xpath="//Item[Name[text()='ams']]//ArgumentExpression" value="https://www.myserver.com/Home.aspx?TID={session}&amp;amp;cid={cid}&amp;amp;Username={username}&amp;amp;uiculture={uiculture}" />