Chinese observers have called on the government to build more advanced and better-armed law enforcement vessels to safeguard the country's sovereignty over the Diaoyu Islands in the East China Sea, following Tokyo's earmarking of millions of dollars to beef up the Japan Coast Guard's (JCG) fleet.

Japan's Kyodo News reported that the JCG is set to receive more patrol ships, boats and helicopters under the government's 422.6 billion yen ($5.3 billion) economic stimulus package authorized Friday.

Japan's Ministry of Land, Infrastructure, Transport and Tourism, which oversees the JCG, is seeking 16.9 billion yen in outlays in the package for the coast guard's procurement of four 1,000-ton patrol vessels, three 30-meter-long patrol boats and three helicopters that can fly in rough weather, among others, Kyodo reported.

It said the additional hardware had been planned for orders under next fiscal year's budget, but the ministry decided to include it in the stimulus plan in light of recent maritime activities by Chinese ships.

According to Kyodo, four Chinese marine surveillance ships Friday morning entered the contiguous zone adjacent to waters off the Diaoyu Islands. One of the vessels contacted a JCG ship using an electric bulletin board and radio, urging the Japanese to observe Chinese law and exit the waters near the islets.

On Thursday, China's State Oceanic Administration (SOA) said on its website that a fleet of marine surveillance vessels spotted four Japanese patrol ships in the waters off the islets, and told them to stop their infringing acts and leave China's territorial waters.

The SOA said that after two typhoons hit the area, the fleet went back to waters off the islets on October 20, and is now continuing their law enforcement missions there.

Jin Yongming, a researcher with the Institute of Law at the Shanghai Academy of Social Sciences, told the Global Times Friday that the spending was meant to financially support the JCG's activities in waters surrounding the Diaoyu Islands, which would pose challenges for China's marine surveillance and fishery administration vessels' law enforcement missions in the area.

In an earlier interview with the Xinhua News Agency, Liu Cigui, head of the SOA, said China's marine surveillance authority now has more than 10,000 personnel, 10 aircraft and over 400 vessels, 27 of which are above 1,000 tons. Liu also noted that 36 large-tonnage vessels are under construction, and will be put into service in one or two years.

Among the 36 vessels, seven are 1,500-ton ships, 15 are 1,000-ton and 14 are 600-ton, Xinhua reported.

The Beijing Evening News opined that Japanese patrol ships outmatch Chinese vessels in their tonnage, speed and confrontational capacity.

"Given the small tonnage and limited number of patrol ships, it's impossible to assign a vessel for every square kilometer of our territorial waters. It couldn't meet the need to protect our marine resources and interests," said the paper.

Jin said Chinese law enforcement vessels do not carry weapons, while Japanese ships are armed with light and medium weapons.

"We ought to build larger, more advanced vessels that are better equipped," Jin said, noting that it's necessary for the country to enact regulations for law enforcement in its territorial waters.

Meanwhile, Japanese media reported that Japan's Defense Minister Satoshi Morimoto said the Sino-Japan maritime dialogue mechanism had been suspended due to the recent row.

Chinese foreign ministry spokesman Hong Lei Friday declined to confirm the suspension when asked at a regular press briefing.