Thai King Bhumibol Adulyadej has expressed concern about next week's court ruling on whether the country's two main parties should be disbanded.
King Bhumibol is highly revered throughout Thailand
"You have the responsibility to prevent the country from collapsing," he warned Constitutional Court judges in a rare televised address late on Thursday.
He said that whatever the verdict, the judges would face criticism.
King Bhumibol, who has been on the throne for more than 60 years, is highly revered by his people.
While he has no formal political power, his interventions are taken very seriously by the country's political leaders.
The Constitutional Court is due to decide on 30 May if the former ruling Thai Rak Thai (Thais Love Thais) Party and its main opposition Democrat Party violated election law during last year's political crisis.
A series of street protests led to Thai Rak Thai calling a snap election, which the Democrat Party boycotted.
In the aftermath of the poll, both parties were accused of trying to manipulate results, violating election laws. The election was later annulled, and after weeks of turmoil the military staged a bloodless coup.
If the Constitutional Court judges find the two parties guilty, both face being disbanded.
Their top leadership, including former Prime Minister Thaksin Shinawatra who is currently in exile abroad, could be banned from politics for five years.
King Bhumibol told the court's judges: "I urge you to prepare yourself to be ready to criticise or be criticised in the capacity of learned men, to prevent the country from falling into a crisis."
Mr Thaksin's Thai Rak Thai party could be disbanded
The ruling is "highly important", he added. "Whatever the verdict is, it will bring damage to the country."
Analysts say the king seems to be implying that either supporters of Mr Thaksin or supporters of the generals who ousted the former prime minister in September's coup are bound to be annoyed by the verdict.
There are fears that a ruling against Thai Rak Thai might prompt street demonstrations, with a former Thai Rak Thai deputy threatening to mobilise thousands of protesters if the court rules against it.
The authorities have already warned they will impose an emergency decree if the situation gets violent.
But if Thai Rak Thai is not disbanded, analysts fear that the justification for the military coup that ousted Thai Rak Thai would be undermined.
Traditionally the king rarely makes public addresses such as the one on Thursday evening.
But this was his second in just over a year - a fact some analysts say is indicative of the nation's ongoing political turmoil.
King Bhumibol has seen 24 prime ministers, 18 coups and 17 constitutions during his 60-year reign.
The military-appointed government which came to power after the September takeover has promised that new elections will be held by the end of this year, after a fresh constitution has been drafted and submitted to a referendum.