Class nb (spdep) from class igraph

Is there a simple way to produce an nb object (in spdep) from a weighted 
or unweighted undirected graph (in igraph).

Could the output of igraph::graph.adjacency(x) be converted to class nb?

Alternatively, igraph::graph.edgelist(x) could be manipulated into class 
Graph, and then spdep::graph2nb() used.

Am I missing an obvious way to do this?

Thanks,
Paul

Paul Galpern
Natural Resources Institute
70 Dysart Road
University of Manitoba
Winnipeg, Manitoba, Canada R3T 2M6
http://borealscape.ca