Japan's Liberal Democratic Party swept to power in Sunday's parliamentary elections, allowing the conservatives and their allies to form a new government expected to pursue a more hawkish security agenda and assert bold economic reforms.

The LDP, which once dominated Japanese politics, will again hold power after three years of center-left rule, returning former prime minister Shinzo Abe to power.

Exit polls showed the LDP had won nearly 300 seats and its coalition partner, New Komeito, about 30 in the more powerful 480-seat lower house of parliament. That could secure a two-thirds majority – enough to override the upper house, where the ruling Democratic Party of Japan is the largest single party.

The DPJ is projected to lose more than two-thirds of its seats in the lower house. Prime Minister Yoshihiko Noda said the defeat is his personal responsibility and resigned as head of the party. The outgoing prime minister is projected to hold onto his seat in parliament.

Analysts say the LDP win will bring in a government promising a tough stance with China over territorial disputes in the Pacific, and government backing for a pro-nuclear energy policy, despite Japan's 2011 nuclear catastrophe.

Mr. Abe has also called for increased public works spending and an easy monetary policy to pull Japan's once-vibrant economy from its fourth recession in the past 12 years.

The country remains in a two-decade economic slump, and voter dissatisfaction in 2009 allowed Mr. Noda's DPJ party to wrest power from conservatives, who had dominated Japanese politics for most of the post-World War two era.

Since the landslide DPJ win, critics say the party has failed to deliver on a series of promises, including vows to crack down on wasteful government spending, and promises of cash incentives to encourage young couples to start families.