Reuters is seeking assurances from the eight banks that own TradeWeb, the bond dealing network it is trying to buy for a possible $300m (€264m), that they will not boycott the portal once they no longer own it, according to a source close to the UK group.

The source said Reuters hoped to tie up a deal by the end of next month if it is satisfied the banks will continue to place business through the network. Reuters is being advised by Lehman Brothers.