At least 27 Houthi-led Shiite rebels were killed and dozens of others were wounded in the ongoing clashes with pro-government tribesmen in northern Yemen, the Interior Ministry said late Monday. The ministry said on its website that the clashes erupted several days ago between northern rebels and Al-Jalha tribe, which is loyal to the government, in Monabih district in the northern province of Saada. 'The fighting is still ongoing,' said the ministry, adding that 'there was no available casualty report about tribesmen and the cause behind the clashes has not yet known.' Yemen has witnessed sporadic battles since 2004 between government troops and rebels. The government has been accusing the rebels of seeking to re-establish the clerical rule overthrown by the 1962 revolution that created the Yemeni republic. On Aug. 26, the Yemeni government and Shiite rebels signed an agreement in Doha to cement a February fragile ceasefire in northern Yemen. On Feb. 11, the government and Shiite rebels struck a truce deal to end a six- year sporadic conflict. Both sides, however, repeatedly trade accusations of breaching the truce which still holds so far. 