Russia is planning "appropriate" measures in response to Britain`s announcement of the expulsion of four Russian diplomats from London, Russia`s foreign ministry said Tuesday. "We are carefully analysing London`s official position... with the aim of drawing up and taking appropriate measures in response," ministry spokesman Mikhail Kamynin said in the statement. Kamynin on Monday called Britain`s decision on diplomatic sanctions "immoral" and warned that the measures "cannot but lead to the most serious consequences in British-Russian relations as a whole." The ministry is expected to make a formal announcement on the diplomatic dispute with Britain at 5:30pm (1330 GMT), officials said earlier, as calls mounted for a firm response from Moscow. Russian newspapers on Tuesday termed the expulsions an act of "diplomatic war." British newspapers meanwhile broadly supported diplomatic moves against Russia as "appropriate." Britain announced the measures, including visa restrictions on Russian officials, in retaliation against Moscow`s refusal to extradite the chief suspect in the murder of former Russian agent Alexander Litvinenko last year. Litvinenko died of radiation poisoning last November and his friends were quick to point the finger of blame at the Kremlin. The Russian government has denied any involvement in the murder. Russia says its constitution prevents it from extraditing its own citizens to face trial in another country, while Britain says this is possible under an international accord signed by Russia. Russian members of parliament quoted by Russian news agencies expressed bewilderment at London`s announcement and broadly supported a strong response from Russia. Member of parliament Alexander Babakov of the pro-Kremlin For a Just Russia party expressed support for "any action taken by Russian authorities to defend the interests of our country," Interfax news agency reported. Russia should show "pragmatism, toughness and consistency," Babakov said. But Leonid Slutsky, a parliamentarian from the pro-Kremlin Liberal Democratic party, told Echo of Moscow radio that Russia should hold back. "If Russia responds, it will be seen as the latest tiff with Europe, and Russia is unlikely to find allies in Europe," he said. Mikhail Margelov, head of the international affairs committee in the Russian senate, called on Britain "to return into the context of legality" for the sake of long-standing bilateral relations. Other Russian members of parliament earlier hinted that Russia`s response could involve a reciprocal expulsion of British diplomats -- a direct diplomatic retaliation common during the Cold War era. "The new British prime minister has declared war on Russia -- a diplomatic one," the pro-Kremlin daily Izvestia said. "It won`t be long before there is an `appropriate response` from Moscow." "Great Britain and Russia have begun a diplomatic war," daily Kommersant said, warning that "Moscow`s reaction, judging from yesterday`s emotional commentary from Russian officials, will be even more violent." Other newspapers stressed the issue of Russia`s constitution, which bars extraditions. "Miliband`s response: London asks Moscow to change its constitution," ran a headline in the Vedomosti business daily. "The proposal by Britain of changing the Russian constitution for the Litvinenko case is reminiscent of colonial times," Boris Makarenko, a political analyst, was quoted by Vedomosti as saying. Konstantin Kosachyov, the head of the international affairs committee in the Russian parliament, struck a similar tone in comments broadcast on Monday, saying that Russia should not be treated as a "banana republic." The dispute comes amid rising tensions between Moscow and the West. Russia has reacted angrily to US plans to deploy an anti-missile defence system in central Europe, suspended its participation in a key European arms treaty and opposed any moves towards independence for Kosovo.