Seoul, Sep 29 (IANS): Four in 10 foreigners who illegally stayed in South Korea last year entered the country without visas and stayed beyond the visa-free period, data from the justice ministry showed.

The number of "illegal aliens" in South Korea came to 423,675 as of the end of last year, accounting for 16.9 per cent of the total foreigners staying in the nation, according to the data cited by Rep. Song Seong-jun of the ruling People Power Party.

Of the illegal foreigners, the number of those who arrived in South Korea without visas reached 190,000, or 44.9 per cent. Foreigners are allowed to enter South Korea without visas in cases of visa exemption (B-1) and tourists in transit (B-2), Yonhap news agency reported.

The number of illegal aliens who entered South Korea with a visa waiver came to 169,000, the largest proportion for a single category at 40 per cent, followed by those with a short-term stay visa at 87,000. Those with B-2 status reached 21,000, the data showed.

Such foreigners are believed to be illegally staying in South Korea to engage in economic activities without proper employment visas.

By nationality, the number of Thais who illegally stayed in South Korea reached 145,000, the largest share of 76.3 per cent, followed by Chinese with 15,000 and people from Kazakhstan with 11,000, the data showed.

The South Korean government suspended visa waiver programs with Pakistan in 2001 and Bangladesh in 2008, citing a sharp rise in illegal foreigners from those nations.