\RequirePackage{hyperref}

\DeclareRobustCommand*{\biburl}{\hyper@normalise\biburl@}
\begingroup
  \catcode`\$=6
  \catcode`\#=12
  \gdef\biburl@$1{\expandafter\biburl@split$1##\\}
  \gdef\biburl@split$1#$2#$3\\{%
    \def \@biburl{\hyper@@link{$1}{$2}}%
  }
\endgroup
\let \@biburl \empty
\let \@@biburl \empty

\let \latex@thebibliography \thebibliography 
\def \thebibliography #1{%
  \latex@thebibliography {#1}%
  \let \latex@bibitem \bibitem \let \bibitem \new@bibitem 
  \let \latex@biblabel \@biblabel \let \@biblabel \new@biblabel
}

\def \new@bibitem {%
  \let \@@biburl \@biburl \let \@biburl \empty
  \latex@bibitem
}

\def \new@biblabel #1{%
  \ifx \@@biburl \empty 
    \latex@biblabel{#1}%
  \else
    \latex@biblabel{\@@biburl{#1}}%
    \ifx \latex@biblabel \NAT@biblabel
      \@@biburl{\large\ensuremath{\triangleright}}%
    \fi
  \fi
}