South Sudan's President Salva Kiir said on Tuesday that Sudan has declared war on his country.

It [this visit] comes at a very critical moment for the Republic of South Sudan because our neighbor in Khartoum has declared war on the Republic of South Sudan, Kiir told Chinese President Hu Jintao at the start of his state visit to Beijing.

Each side has said as much countless times since South Sudan seized the border town of Heglig earlier this month. The south has since withdrawn troops from the area but violence continues along the border, and Kiir's latest statement comes after the second day of bombing in South Sudan's Unity State.

South Sudan blames Sudan for dropping eight bombs in the town of Panakuac on Tuesday, which Sudan has denied. Ground fighting has been going on in Panakuach since last week.

South Sudan has also blamed Sudan for the bombing of a market in Unity on Monday that killed two people, including a child, and injured a dozen more.

Yesterday evening and yesterday night there was heavy bombardment by Antonov aircraft of the Sudanese army of the areas of Lalop market and Panakuach, Unity State Governor Taban Deng Gai told Reuters.

Although there has yet to be an official declaration of war from either side, both have come close. Sudan's government declared being in a state of war two weeks ago and President Omar al-Bashir said last Wednesday that our main goal is [the] liberation of South Sudan, which became independent from the north just last July.

From today our slogan is to liberate the citizens of South Sudan from the rule of the SPLM [Sudan People's Liberation Movement], and from today it will be eye for eye, tooth for tooth and strike for strike, Bashir said.

On Monday, United Nations Secretary General Ban Ki-moon condemned the bombings, but also called Kiir and urged him to stop the slide toward further confrontation and ... to return to dialogue as a matter of urgency, according to the BBC.

Kiir's visit to Beijing will last five days, and he will meet with China's top leaders to discuss the two nations' economic and diplomatic relationships. The South Sudanese president described Beijing as one of our economic and strategic partners, and China, which is heavily invested in both Sudan and South Sudan, could play a role if an all-out war between the two nations begins, either as a moderator or as an arms dealer.