(Adds spokesmen of Putin, foreign ministry)
By Steve Gutterman
MOSCOW, July 20 (Reuters) - Russia dismissed international criticism of its veto of a U.N. Security Council resolution on Syria as "absolutely unacceptable" and assailed U.S. plans to work outside the council to increase pressure on President Bashar al-Assad.
Russia and China both vetoed a draft resolution on Thursday that would have threatened Syrian authorities with sanctions if they did not halt their violent crackdown on a 16-month-old revolution.
Western nations condemned the vetoes and Britain's U.N. envoy said Russia and China's action effectively " a brutal regime".
Russian Foreign Ministry spokesman Alexander Lukashevich rejected the criticism, saying the draft resolution placed unrealistic demands on the government while putting little or no pressure on its opponents.
"Instead of making crude insinuations about Russian policy ... our Western partners should do at least something to encourage the militant opposition to step onto the path of a political settlement," Lukashevich told a weekly briefing.
The veto was the third time Russia and China have blocked Western efforts to increase pressure on Assad.
The U.S. ambassador to the United Nations, Susan Rice, said after the veto that the United States would "intensify our work with a diverse range of partners outside the Security Council to bring pressure to bear on the Assad regime" and deliver aid.
Lukashevich said: "If such declarations and such plans are elements of actual policy, I think that is a very, very alarming signal to all of us about how the international community plans to respond to international conflict situations."
President Vladimir Putin issued a similar warning after a meeting of Russia's presidential Security Council that included a detailed discussion of Syria, his spokesman Dmitry Peskov said.
Putin believes that "any attempts to bypass the U.N. Security Council will be ineffective and undermine the authority of this international organisation," Russian news agencies quoted Peskov as saying. (Editing by Alissa de Carbonnel and Tim Pearce)