The seizure is the second largest ever made in Norway of the chewable leaf, which, while illegal in Norway, is the favoured drug of many Yemeni and Somali immigrants.
"Two vehicles with Swedish license plates were stopped," Paul Johan Ask of the Oslo Customs told VG newspaper. "In one car the seats were filled up with 64 banana boxes that contained a total of 392 kg of khat.
Customs officials in Svinesund on the Swedish border seized 524 kilograms of the drug in late December.
The car was driven by a 43-year-old Portuguese man resident in the UK.
This month, huge consignments of cocaine have been discovered in boxes of bananas exported from South America, at supermarket warehouses in both Germany and Sweden.
Officers found 140 kg of the drug hidden among bananas at five Aldi stores in Germany, while in December Swedish police found 145 kg in a warehouse run by Bama, one of the country's largest wholesalers.