Russian foreign minister Sergei Lavrov Monday considered as \"very difficult\" the preparations for a second international conference on Syria. \"We have discussed how to proceed in our efforts to hold a peace conference over Syria in a bid to stop more bloodshed ... It is not an easy task but very difficult,\" Lavrov told a joint news conference with his US counterpart John Kerry following their talks here. He said Russia was keen on expanding participants in the Geneva II conference to include \"all players\" in the region, in a reference to Iran whose participation is opposed by Western countries. Kerry said the US and Russia was committed to principles of the Geneva meeting that was held last June, which called for formation of a transitional government in a bid to end the conflict that killed more than 80,000 people. Kerry and Lavrov, meeting for the sixth time since the former took office, voiced concern over use of chemical weapons in Syria, affirming importance of concrete evidence over these claims. France had earlier today called on the Syrian opposition to name their representatives to the Geneva II meeting.