The disappointing performance in Friday's goalless draw with Scotland has led to calls from pundits and fans for Southgate to adopt a more positive style.
In a separate statement, the ministry also announced the expulsion of three Slovak diplomats, who must leave by May 5, and accused Bratislava of "false solidarity" with Prague.
Russia retaliated by ordering out 20 Czech diplomats -- sparking an angry ultimatum from Prague for Moscow to let them return or face further expulsions from its embassy.
"I expect that also on the basis of this..., we will learn about more expressions of support and it will be up to member states if they add some concrete decisions."
"The reaction (by Russia) is stronger than we had expected, it is more diplomats than the number of intelligence officers we expelled," Hamacek told a televised news conference.
A statement issued by the PPF Group N.V. a privately held international financial and investment group founded in 1991 by the 56-year-old billionaire stated that Kellner was killed in a helicopter crash on March 27 in a mountainous area of Alaska.