Thats a very high grade switch you are after. The reason is that when a switch breaks a circuit, there is an arc (spark) as its contacts part. With AC the voltage goes through zero every 20mS so the arc can never last more then this time. With DC the arc is maintained until the switch contacts have parted wide enough for the voltage not to be enough to jump the gap, so the arc lasts a much longer time. In general a 10A 230V AC switch is rated for 10A 12V DC. That says it all. If you really can't find a switch (that you can afford), use a high voltage power transistor as the main switch and switch the base current instead.
Frank