* Pressure mounting on Algeria over Mali crisis
* Algeria fears return of al Qaeda if forced out of Mali
U.S. Secretary of State Hillary Clinton pressed regional power Algeria on Monday to support an Africa-led military intervention in northern Mali, a senior U.S. official said.
Clinton's one-day visit comes amid mounting international pressure on Algeria over the crisis in Mali, where a March military coup was followed by a revolt that has seen Tuareg rebels and Islamist militants, some linked to al Qaeda, seize control of the northern two-thirds of the country.
The senior U.S. official said after the talks that Clinton argued strongly that counter-terror efforts in Mali could not wait for a political resolution to Mali's problems.
"The secretary underscored ... that it is very clear that a political process and our counter-terrorism efforts in Mali need to work in parallel," the official said.
"We have an awful lot at stake here, and an awful lot of common interests, and there's a strong recognition that Algeria has to be a central part of the solution," the senior U.S. official told reporters traveling with Clinton.
"They are going to be supportive of a major effort in Mali to both restore democracy and restore order in the North. Everyone has their favorite institutions to work with, and there's a lot that has to be sorted out in the geometry of the thing," the official said before Clinton's talks with Algerian President Abdelaziz Bouteflika.
Africa's biggest country, and a top oil and gas exporter, Algeria shares a 2,000-km (1,250-mile) border with Mali and sees itself as the major regional power, wary of any outside interference.
It fears military action in Mali could push al Qaeda militants back into southern Algeria as well as triggering a refugee and political crisis, especially among displaced Malian Tuaregs heading north to join tribes in Algeria.
Algeria repeatedly has advocated a diplomatic solution to the Mali crisis, and ruled out intervention itself.
Although Algiers would not be able to veto an intervention operation by other countries, it would be diplomatically risky for African states backed by Western powers to intervene in Mali without its consent, especially as the conflict could drag on for many months.
Clinton's visit to Algiers came after a high-level meeting in the Malian capital Bamako on Oct. 19 that brought regional and international players to the negotiating table, and after which French and Algerian sources said Algeria had "tacitly" agreed to intervention.
France, the region's former colonial power, drafted a U.N. Security Council resolution urging Mali to engage in dialogue with Tuareg Islamist rebels Ansar Dine if they cut links with radical groups, a move that satisfied Algiers' calls for dialogue.
Paris had until now considered Ansar Dine among the al Qaeda-linked groups and refused to negotiate with them.
The resolution also asked African states and the United Nations for a Mali military intervention plan led by the West African ECOWAS block within 45 days.
U.S. officials said Clinton planned to underscore that Algeria would be crucial to any future mission in Mali, noting both its military power and the strength of its intelligence gathering network in the region.
A second official said it appeared Algeria was "beginning to warm to the idea" of an ECOWAS-led military intervention, but this would be contingent on the West African block putting forward a fully-developed plan which it has yet to do.