Converting tab or txt file into gxl file using R programming

Question

[mail2steff]

Dear All, I have a tab delimited file with following columns

> otu1      otu2      counts
> OTU_1     OTU_2       0 
> OTU_1     OTU_3       1 
> OTU_1     OTU_4       1 
   : 
   :
   :

here otu1 is the source node and otu2 is the target node. count is the edge. how can I converted into gxl file using r or any other programming?