Japan's trade deficit widened sharply to a record in 2013 as import costs outpaced export receipts due to a weaker yen and higher fuel bills, and the third straight annual shortfall was a reminder of the challenge facing Prime Minister Shinzo Abe.
The record run of annual deficits by a nation that for decades had racked up hefty trade surpluses has raised questions about how Japan can fund and contain public debt of more than $10 trillion, or more than twice the size of its economy.
Abe's reflationary policies have weakened the yen, driving up the value of export receipts in yen terms and boosting exporters' earnings, but so far have failed to shore up volumes.
(Read more: Japan Inc, is your 'animal spirit' calling?)
Economists have anticipated a so-called "J-curve" effect from the weak yen, where a spike in import costs would over time be more than offset by gains in exports.
But the currency's decline has not led to the export turnaround needed to bring the trade balance back into the black, in part because exporters have not yet passed on their price advantage to customers overseas.
"If corporate Japan now comes to believe that the yen will stay weak or even continue to wobble, export prices may tumble," HSBC economists said in a report. "Then shipments would soar and Japan's competitors, like Korea, may finally feel a squeeze."
Ministry of Finance data on Monday showed exports rose 9.5 percent in 2013, the first gain in three years, but export volumes fell 1.5 percent, a third consecutive fall.
(Read more: Why Japan's rocky January won't deter bulls)
Japan's annual trade gap was a record 11.47 trillion yen ($112 billion), about two-thirds larger than 2012's 6.94 trillion yen shortfall. It was the third straight annual deficit, the longest run in the data that goes back to 1979.
Analysts say monthly trade deficits may narrow in coming months as a global recovery boosts export demand and a surge in consumer spending eases after a sales tax increase in April.
The MOF data showed exports rose 15.3 percent in December from a year earlier, led by car exports to the United States, a key market. While below economists' median forecast for a 17.8 percent gain, it was a 10th straight month of gains.
Imports rose 24.7 percent in December from a year earlier, against an expected 26.1 percent gain. Import costs have risen both due to the weaker year and higher fuel imports after Japan shut down nuclear power plants following the Fukushima disaster in 2011.
(Read more: Nikkei at 25,000? Nomura thinks so)
Japan's current account logged a record deficit in November, remaining in the red for second month.
Some analysts say trade shortfalls could pull the current account into the red in coming years, meaning that Japan may start chipping away at its vast pool of domestic savings and increasing the need to rein in its huge public debt.