Manila - A severe tropical storm has gained strength as it moves closer to the Philippines and may intensify further into a typhoon, bringing moderate to heavy rains and blustery weather on Christmas Day, the biggest holiday in the predominantly Roman Catholic nation, weather forecasters say.Tropical Storm Nock-Ten was 790km east of Guiuan town in the eastern part of the country on Friday morning, packing winds of up to 105km/h and gusts of up to 130km/h. A deputy administrator of the government weather bureau, Landrico Dalida Jun, said Nock-Ten might intensify into a typhoon, with winds of at least 120km/h before it makes landfall in the eastern part of the country late on Sunday."Our Christmas will be rainy, with strong winds," Dalida said. "So while we celebrate, let us also prepare."Officials warned of possible landslides and flooding along the typhoon's path and storm surges in coastal areas that makes sea travel risky. Stormy weather can be expected starting Saturday evening, they said.