Estonian Foreign Minister Kristiina Ojuland has been sacked by President Arnold Ruutel after secret files disappeared from her ministry.
Kristiina Ojuland's party now may quit the government
The move came after a security check found that almost 100 documents - mostly relating to Estonia's position at various EU summits - were missing.
Ms Ojuland, 38, said most of the files disappeared before she took over.
The sacking could lead to the collapse of the Baltic nation's centre-right coalition government, experts warn.
Ms Ojuland's Reform Party - part of a three-party coalition - has accused Prime Minister Juhan Parts of sparking a political crisis by calling for her dismissal.
If the party decides to pull out of the coalition, the government would be left in a minority with just 41 seats in the 101-seat parliament.
Mr Parts earlier this week called for Ms Ojuland to be sacked after a routine audit of the foreign ministry found that 91 secret document were missing.
"Foreign policy is based on trust, and Kristiina Ojuland has lost it," Mr Parts said.
Ms Ojuland refused to step down and was sacked by a presidential decree on Thursday.
The missing documents date from 1996 to 2004.
Ms Ojuland - who became foreign minister in January 2002 - has repeatedly insisted she does not feel responsible.
On Thursday, she accused Mr Parts of "acting in a stormy way, without talking to the government partners first".
Ms Ojuland said the Reform Party would discuss next week whether to stay in the government.
Last year, Defence Minister Margus Hanson resigned after a briefcase with secret document was stolen from his house.