According to the Foreign Office, the United Kingdom is to brief the UN Security Council on the poisoning of a former double agent from Russia later.
Russia has not yet responded to a midnight deadline set by Theresa May to explain how a Russian-made nerve agent was used on Sergei Skripal and daughter Yulia.
The PM is set to announce a series of measures against Russia ahead the UN meeting, to be held at 19:00 GMT.
Russia said it had "no motive" in the attempted murder of the pair.
The Kremlin, which has consistently declined involvement, said any steps by the PM would lead to "retaliatory measures".