MPs in Khartoum brand South Sudan 'enemy' state
Sudanese MPs have voted unanimously to brand South Sudan "an enemy".
"The government of South Sudan is an enemy and all Sudanese state agencies have to treat her accordingly," the resolution said.
A Khartoum information ministry official told the BBC the move was linked to South Sudan's seizure last week of the Heglig oil field.
South Sudan had accused Sudan of launching attacks on its territory from the frontier oil field.
The country seceded from Sudan in July last year following a civil war which ended in 2005.
But a number of major disputes remain, including over oil and the official demarcation of the international border, and there have been a number of clashes since.
UN camp bombed
The BBC's James Copnall in Khartoum says the full ramifications of the parliamentary vote are not clear, but it is evident that both countries are close to a full war.
The speaker of parliament, Ahmed Ibrahim al-Tahir, called for Sudan to overthrow the South Sudanese government, the AFP news agency reports.
Dr Khalid Al Mubarak, London's Sudan embassy spokesperson, told the BBC's Focus on Africa programme that South Sudan has made itself an enemy by crossing the border and occupying Sudan's land.
"It is not the people of the south but the government that is the real enemy and we know how to confront them," Rabbie Abd al-Attie, a senior adviser to Sudan's information minister, told the BBC.
Khartoum has vowed to use "all means" to recapture Heglig - but Sudanese officials deny Monday's vote amounts to a declaration of war, adding that Sudan does not want an all-out war but simply needs to regain its territories.
Heglig, which used to provide more than half of Sudan's oil, is internationally accepted to be part of Sudanese territory - although the border area is yet to be demarcated.
The parliamentary vote in Khartoum came as a UN spokesman confirmed that Sudanese planes had bombed a UN peacekeepers' camp in South Sudan's border area on Sunday.
No-one was hurt during the attack on the small UN base in Mayom village in Unity state, Kouider Zerrouk said.
But at least 15 people have been killed in other bombing raids in South Sudan over the weekend, eyewitnesses told the BBC.
The African Union has demanded South Sudan's unconditional withdrawal from Heglig, calling its occupation "illegal and unacceptable", but also condemned Sudan for carrying out aerial bombardments of South Sudan.
Sudan has denied being behind the air raids.
On Thursday, the UN Security Council called for an "immediate" ceasefire and expressed "deep and growing alarm at the escalating conflict".