A People's Liberation Army Navy (Plan) attack submarine from China docked in Sabah recently, marking this the second such docking of Chinese naval vessels in Malaysia this year.

According to defence magazine Jane's 360, the visit took place sometime between Sept 8 and 11 at the Royal Malaysian Navy's submarine base in Teluk Sepanggar, Sabah.

This, says the report, coupled with a similar visit earlier this year, was "a sign of deepening defence relationships between two South China Sea claimant states."

The report said it was not clear which submarine was involved, whether it was like a Yuan (Type 039A/B) class or Song (Type 039) class diesel-electric boat (SSK).

The submarine was reportedly escorted by a Plan's Dajiang (Type 925) class submarine support and salvage ship Chongmingdao.

According to the report, the Yuan and Song classes are equipped with six 533mm tubes, which are capable of launching a variety of missiles and torpedoes.

These submarines are known to carry the Yu-4 acoustic homing torpedo, which carries a 309kg warhead.

Malaysia and China are experiencing warming ties amidst tensions over rights to the South China Sea among Asean countries.

Last year, Malaysia procured four Littoral Mission Ships (LMS) from China.

This was followed by the docking of three Chinese warships – CNS Changchun Type 052C destroyer, CNS Jingzhou Type 054A frigate and CNS Chaohu Type 903 replenishment ship – in Penang in May.