UNITED NATIONS — The United Nations Security Council, facing staunch opposition from Russia, failed to pass a resolution on Thursday that would have imposed a 30-day cease-fire in Syria to allow humanitarian aid to reached a besieged Damascus suburb.

With new reports on Thursday of a rocket attack that took 42 lives, the death toll this week in the rebel-held suburb, eastern Ghouta, rose to more than 300.

The suffering of civilians in Syria “brings shame on all of us,” Britain’s representative, Stephen Hickey, said at the Security Council meeting. He described the conditions in eastern Ghouta as a “hell on earth.”